* Replace all semaphores with task notifications.
* use critical sections to prevent concurrent data access.
* Ensure scan stop has been called before connecting.
* Optimize and cleanup
* Add template casting to NimBLERemoteDescriptor::readValue()
* Removed storage of the descriptor value read as it did not serve any purpose.
Instead of discovering the peripheral database on connection and consuming
the associated resources this will give the user more control over the
discovery operation.
* Adds void NimBLEClient::discoverAtrributes() for the user to discover all
the peripheral attributes as a replacement for the former functionality.
* getServices(), getCharacteristics(), getDescriptors() now take an
optional bool parameter (default false).
If true it will clear the respective vector and retrieve all the respective
attributes from the peripheral. If false it will retrieve the attributes
only if the vector is empty, otherwise the vector is returned with the
currently stored attributes.
* getService(NimBLEUUID), getCharacteristic(NimBLEUUID), getDescriptor(NimBLEUUID)
will now check the respective vectors for the attribute object and, if not
found, will retrieve (only) the specified attribute from the peripheral.
This allows NimBLE options in menuconfig to reduce code size based on
the roles selected (scan/advertising/central/peripheral).
Significant code space can be saved by removing unnecessary roles for the application.
