Add iterators to client remote attributes.

Add iterators for NimBLEScan: NimBLEadvertisedDevice, NimBLEClient: NimBLERemoteService, NimBLERemoteService: NimBLERemoteCharacteristic and NimBLERemoteCharacteristic: NimBLERemoteDescriptor

This is handy e.g. for showing every address of the advertised devices from a scan. To do so, first get a new scan and next:
```
for(auto pAdvertisedDevice: pBLEScan->getResults()) {
  Serial.printf("Address is %s\n", std::string(pAdvertisedDevice->getAddress()).c_str());
}
```
Of course any other property of the advertised device can be shown (or looked up, if that is your use case)

Also this is handy e.g. for showing every UUID in a peripheral. To do so, first connect to a peripheral and next:
```
for(auto pService: *pClient) {
  Serial.printf("Service UUID is %s\n", std::string(pService->getUUID()).c_str());
  for(auto pCharacteristic: *pService) {
    Serial.printf("Characteristic UUID is %s\n", std::string(pCharacteristic->getUUID()).c_str());
    for(auto pDescriptor: *pCharacteristic) {
      Serial.printf("Descriptor UUID is %s\n", std::string(pDescriptor->getUUID()).c_str());
    }
  }
}
```
Again of course any other property can be shown, or looked up.

src/NimBLEClient.cpp

@@ -348,6 +348,24 @@ int NimBLEClient::getRssi() {
 } // getRssi
 
 
+/**
+ * @brief Get iterator to the beginning of the vector of remote service pointers.
+ * @return An iterator to the beginning of the vector of remote service pointers.
+ */
+std::vector<NimBLERemoteService*>::iterator NimBLEClient::begin() {
+    return m_servicesVector.begin();
+}
+
+
+/**
+ * @brief Get iterator to the end of the vector of remote service pointers.
+ * @return An iterator to the end of the vector of remote service pointers.
+ */
+std::vector<NimBLERemoteService*>::iterator NimBLEClient::end() {
+    return m_servicesVector.end();
+}
+
+
 /**
  * @brief Get the service BLE Remote Service instance corresponding to the uuid.
  * @param [in] uuid The UUID of the service being sought.

src/NimBLEClient.h

@@ -43,6 +43,8 @@ public:
     int                                         getRssi();                     // Get the RSSI of the remote BLE Server
 
     std::vector<NimBLERemoteService*>*          getServices();                 // Get a vector of the services offered by the remote BLE Server
+    std::vector<NimBLERemoteService*>::iterator begin();
+    std::vector<NimBLERemoteService*>::iterator end();
     NimBLERemoteService*                        getService(const char* uuid);  // Get a reference to a specified service offered by the remote BLE server.
     NimBLERemoteService*                        getService(const NimBLEUUID &uuid);   // Get a reference to a specified service offered by the remote BLE server.
     std::string                                 getValue(const NimBLEUUID &serviceUUID, const NimBLEUUID &characteristicUUID);   // Get the value of a given characteristic at a given service.

src/NimBLERemoteCharacteristic.cpp

@@ -240,6 +240,24 @@ uint16_t NimBLERemoteCharacteristic::getDefHandle() {
 } // getDefHandle
 
 
+/**
+ * @brief Get iterator to the beginning of the vector of remote descriptor pointers.
+ * @return An iterator to the beginning of the vector of remote descriptor pointers.
+ */
+std::vector<NimBLERemoteDescriptor*>::iterator NimBLERemoteCharacteristic::begin() {
+    return m_descriptorVector.begin();
+}
+
+
+/**
+ * @brief Get iterator to the end of the vector of remote descriptor pointers.
+ * @return An iterator to the end of the vector of remote descriptor pointers.
+ */
+std::vector<NimBLERemoteDescriptor*>::iterator NimBLERemoteCharacteristic::end() {
+    return m_descriptorVector.end();
+}
+
+
 /**
  * @brief Get the descriptor instance with the given UUID that belongs to this characteristic.
  * @param [in] uuid The UUID of the descriptor to find.

src/NimBLERemoteCharacteristic.h

@@ -48,6 +48,8 @@ public:
     bool                                           canRead();
     bool                                           canWrite();
     bool                                           canWriteNoResponse();
+    std::vector<NimBLERemoteDescriptor*>::iterator begin();
+    std::vector<NimBLERemoteDescriptor*>::iterator end();
     NimBLERemoteDescriptor*                        getDescriptor(const NimBLEUUID &uuid);
     std::vector<NimBLERemoteDescriptor*>*          getDescriptors();
     uint16_t                                       getHandle();

src/NimBLERemoteService.cpp

@@ -64,6 +64,24 @@ NimBLERemoteService::~NimBLERemoteService() {
 }
 
 
+/**
+ * @brief Get iterator to the beginning of the vector of remote characteristic pointers.
+ * @return An iterator to the beginning of the vector of remote characteristic pointers.
+ */
+std::vector<NimBLERemoteCharacteristic*>::iterator NimBLERemoteService::begin() {
+    return m_characteristicVector.begin();
+}
+
+
+/**
+ * @brief Get iterator to the end of the vector of remote characteristic pointers.
+ * @return An iterator to the end of the vector of remote characteristic pointers.
+ */
+std::vector<NimBLERemoteCharacteristic*>::iterator NimBLERemoteService::end() {
+    return m_characteristicVector.end();
+}
+
+
 /**
  * @brief Get the remote characteristic object for the characteristic UUID.
  * @param [in] uuid Remote characteristic uuid.

src/NimBLERemoteService.h

@@ -39,6 +39,8 @@ public:
     virtual ~NimBLERemoteService();
 
     // Public methods
+    std::vector<NimBLERemoteCharacteristic*>::iterator begin();
+    std::vector<NimBLERemoteCharacteristic*>::iterator end();
     NimBLERemoteCharacteristic*               getCharacteristic(const char* uuid);            // Get the specified characteristic reference.
     NimBLERemoteCharacteristic*               getCharacteristic(const NimBLEUUID &uuid);      // Get the specified characteristic reference.
 //  BLERemoteCharacteristic* getCharacteristic(uint16_t uuid);      // Get the specified characteristic reference.

src/NimBLEScan.cpp

@@ -404,6 +404,24 @@ NimBLEAdvertisedDevice NimBLEScanResults::getDevice(uint32_t i) {
 }
 
 
+/**
+ * @brief Get iterator to the beginning of the vector of advertised device pointers.
+ * @return An iterator to the beginning of the vector of advertised device pointers.
+ */
+std::vector<NimBLEAdvertisedDevice*>::iterator NimBLEScanResults::begin() {
+    return m_advertisedDevicesVector.begin();
+}
+
+
+/**
+ * @brief Get iterator to the end of the vector of advertised device pointers.
+ * @return An iterator to the end of the vector of advertised device pointers.
+ */
+std::vector<NimBLEAdvertisedDevice*>::iterator NimBLEScanResults::end() {
+    return m_advertisedDevicesVector.end();
+}
+
+
 /**
  * @brief Return a pointer to the specified device at the given address.
  * If the address is not found a nullptr is returned.

src/NimBLEScan.h

@@ -44,6 +44,8 @@ public:
     void                                           dump();
     int                                            getCount();
     NimBLEAdvertisedDevice                         getDevice(uint32_t i);
+    std::vector<NimBLEAdvertisedDevice*>::iterator begin();
+    std::vector<NimBLEAdvertisedDevice*>::iterator end();
     NimBLEAdvertisedDevice                         *getDevice(const NimBLEAddress &address);
 
 private: