* General code cleanup.
* `NimBLEAdvertisementData` moved to it's own .h and .cpp files.
* Added new method, `NimBLEAdvertising::setPreferredParams` that takes the min and max preferred connection parameters as an alternative for `setMinPreferred` and `setMaxPreferred`.
* Added new method, `NimBLEAdvertising::setAdvertisingInterval` Sets the advertisement interval for min and max to the same value instead of calling `setMinInterval` and `setMaxInterval` separately if there is not value difference.
* `NimBLEAdvertisementData` payload is now stored in `std::vector<uint8_t>` instead of `std::string`.
* `NimBLEAdvertisementData::getPayload` now returns `std::vector<uint8_t>` instead of `std::string`.
* `NimBLEAdvertisementData::addData` now takes either a `std::vector<uint8_t>` or `uint8_t* + length` instead of `std::string` or `char + length`.
* `NimBLEAdvertisementData::setName` now takes an optional `bool` parameter to indicate if the name is complete or incomplete, default = complete.
* `NimBLEAdvertising::start` No longer takes a callback pointer parameter, instead the new method `NimBLEAdvertising::setAdvertisingCompleteCallback` should be used.
* `NimBLEAdvertising::setAdvertisementType` has been renamed to `NimBLEAdvertising::setConnectableMode` to better reflect it's function.
* Added new method, `NimBLEAdvertising::setDiscoverableMode` to allow applications to control the discoverability of the advertiser.
* Advertising the name and TX power of the device will no longer happen by default and should be set manually by the application.
* Added overload for `NimBLEAdvertising::setManufacturerData` that takes a `const uint8_t*` and , size_t` paramter.
* Added overload for `NimBLEAdvertising::setServiceData` that takes `const NimBLEUUID& uuid`, ` const uint8_t* data`, ` size_t length` as parameters.
* Added overload for `NimBLEAdvertising::setServiceData` that takes `const NimBLEUUID& uuid`, `const std::vector<uint8_t>&` as parameters.
* All `NimBLEAdvertisementData` functions that change data values now return `bool`, true = success.
* All `NimBLEAdvertising` functions that change data values now return `bool`, true = success.
* `NimBLEAdvertising::setMinPreferred` and `NimBLEAdvertising::setMaxPreferred` have been removed, use `NimBLEAdvertising::setPreferredParams` instead.
* All advertising data is now stored in instances of `NimBLEAdvertisingData` and vectors removed from `NimBLEAdvertising`.
* `NimBLEAdvertising::setAdvertisementData` and `NimBLEAdvertising::setScanResponseData` now return `bool`, true = success.
* Added new method, `NimBLEAdvertisementData::removeData`, which takes a parameter `uint8_t type`, the data type to remove.
* Added new method, `NimBLEAdvertisementData::toString`, which will print the data in hex.
* Added new method, `NimBLEAdvertising::getAdvertisementData`, which returns a reference to the currently set advertisement data.
* Added new method, `NimBLEAdvertising::getScanData`, which returns a reference to the currently set scan response data.
* Added overloads for `NimBLEAdvertising::removeServiceUUID` and `NimBLEAdvertisementData::removeServiceUUID` to accept a `const char*`
* Added new method, `NimBLEAdvertising::clearData`, which will clear the advertisement and scan response data.
Refactor attributes to reduce code duplication and improve maintainability.
* Add attribute base classes to provide common code.
* Add const where possible to functions and parameters.
* `NimBLECharacteristic::notify` no longer takes a `bool is_notification` parameter, instead `indicate()` should be called to send indications.
* `NimBLECharacteristic::indicate` now takes the same parameters as `notify`.
* `NimBLECharacteristicCallbacks` and `NimBLEDescriptorCallbacks` methods now take `const NimBLEConnInfo&` instead of non-const.
* `NimBLECharacteristic::onNotify` callback removed as unnecessary, the library does not call notify without app input.
* `NimBLERemoteCharacteristic::getRemoteService` now returns a `const NimBLERemoteService*` instead of non-const.
* Add NimBLEUUID constructor that takes a reference to `ble_uuid_any_t`.
* `NimBLERemoteService::getCharacteristics` now returns a `const std::vector<NimBLERemoteCharacteristic*>&` instead of non-const `std::vector<NimBLERemoteCharacteristic*>*`
* `NimBLERemoteService::getValue` now returns `NimBLEAttValue` instead of `std::string`
* `NimBLEService::getCharacteristics` now returns a `const std::vector<NimBLECharacteristic*>&` instead of a copy of std::vector<NimBLECharacteristic *>.
* Remove const requirement for NimBLEConnInfo parameter in callbacks.
Const is unnecessary as the data can't be changed by application code.
* Change NimBLERemoteCharacteristic::getRemoteService to return const pointer.
* Add length parameter to `setValue()` templates, with defaults for backward compatibility.
* Changed `setValue(const char*)` to add an optional length parameter so that a NULL character can be included, defaults to strlen.
* Moved non-inline functions to `NimBLEAttValue.cpp` file.
* Corrected includes to permit compilation as a stand-alone utility.
* Removed repeated code in `setValue()` by using `append()` after clearing the value.
* General code cleanup.
Adds support for advertising and connections with coded/2M PHY's.
Adds new classes `NimBLEExtAdvertising` and `NimBLEExtAdvertisement`.
When extended advertising is enabled the original advertising classes become unavailable and the new classes must be used.
Changed some return values for advertising methods for consistency with the new classes methods.
Server: Add onSubscribe() callback for characteristics.
Adds a new method to NimBLECharacteristicCallbacks that gets called when a client
changes it's subscription status.
* Remove NimBLE2902 class.
As the NimBLE2902 class usefulness was only related to callback functions that were replaced
by the NimBLECharacteristicCallbacks:onSubscribe() method this removes the NimBLE2902 class and
moves all subscription handling to NimBLECharacteristic.
* Update documents and examples to reflect this change.
* Add getSubscribedCount() to get the number of subscribed clients.
* Use critical sections to access characteristic/descriptor value data.
* Remove unnecessary code
* Create characteristic semaphore only if needed for indications.
* Fix advertising when not broadcasting a service.
