Added a separate example program to test the Satcom message and IridiumSBD files together.
Changed the PPM encoder to use the timer 5, which was changed from timer 4 for APM2. This hasn't been tested yet.
Added base files for Satcom namespace which will be used to make initialization and use of the IridiumSBD class easier. Not totally necessary but it will keep everything else clean.
Added Satcom.cpp to CMakeLists files.
Lots of comm changes. Started writing the message generating code and then we decide to have messages generated automatically by the formats json file. Message are now defined by a struct and the struct will be serialized to send the message. The SatcomMessage file was changed to MessageManager, which better describes its role. MessageManager is in charge of updating message fields (which must be hardcoded), and for serializing the structs and calculating a CRC16 checksum. This is untested and the Messages.h file is missing.