Adding support for zigbee active scan and network join

Also implementing the following bugfixes:

• improving thread safety
• fixing channel switch (proprietary commissioning)

Fixing network creation from factory default

• Fixing a bug in libezsp's startup on dongle that are not already previously part of a network (see issue #73)
• Allowing a reset of the EZSP dongle from Linux using mainEzspTest's command-line option -l

Improving ASH decoding and forcing dynamic allocation for libezsp instances by default

• Fixing ITimer's timeout value from type uint16_t to uint32_t
• Using dynamic allocation for libezsp instances rather than a singleton pattern. This allows to re-init the library or support more than one dongle (in theory)
• Supporting multiple EZSP payload extracts from one ash stream
• Adding libEzsp.getNetworkKey() to API (accessible via mainEzspTest's -k switch)
• Implementing operator<<() on a few classes, including ByteBuffer to allow for easier buffer dump to logs.
• Implementing swap operator on main classes.

Access to dongle hw/sw/stack versions

Example on how to do this can be found here:
https://github.com/Legrandgroup/libezsp/blob/8571574085160bc71177f68795f09b17b3c2ad7f/example/mainEzspStateMachine.h#L105

Note you should check that the libezsp library exports its NSEZSP::CLibEzspState state as NSEZSP::CLibEzspState::READY before you invoke NSEZSP::CEzsp::getAdapterVersion() or you might get an empty or incomplete version returned.

Library major re-architecture and full Green Power support

• Main re-architecture for file structure and classes, using a facade pattern to hide libezsp's internal from the user code.
• Switching to cmake for build auto-configuration.
• Building a shared libezsp library (also with an internal library for SPIs libezspspi), and adding a make install target also publishing header files.
• Adding support for secure MSP channel request from GPDs, allowing channel request support with sensors (proprietary, secure, exchange).
• Allowing to remove GPDs from mainEzspTest command-line arguments.
• Adding an AES SPI (for a future compatibility with other third-party AES crypto libs).
• Adding firmware upgrade mode feature and bootloader prompt escape capability.
• Supporting full GP, including MIC validation.
• Also adding CI using travils+sonarcloud and coverage checking using gcov.
• Updating unit tests, using a mock serial SPI.
• Added many command-line options to sample mainEzspTest.
• Supports custom baudrates on adapter (including 115200 which is now the default)
• Allowing on-host or offloaded (on-adapter) MIC calculation.

Support for GP filtering embedded in the dongle and over the air or offline commissionning

Adding support for Green Power devices filtering on source IDs directly inside the EZSP firmware embedded in the dongle.
Also checking MIC against GP keys and only forwarding valid messages to the caller.

Manual GP commissionning is functional.
Offline (preset of source ID and keys) commissionning is function also.

Support for sample GPD sensors

Adding support for Green Power devices (currently hacked to force filtering inside the lib because of a bug in the dongle's firmware)
Adding command-line options for sample executable

Support for Zigbee 3.0 and build for a sample executable

Support for Zigbee 3.0 and build for a sample executable.