Forked version

Hello again,

This pull request is to let you know about the rework I have done on Pilot Assistant, which might contain some things of interest.

I have refactored most of the code, some changes include:
  * Using "private" instead of "internal" in most places. 
  * Reducing tight coupling between components.
  * Tried to separate GUI drawing and behavioural stuff.

Other changes include:
  * My original GUI changes.
  * The SAS GUI has been redone, and should (hopefully) be simpler to understand. 
  * Text fields now have input lock, this blocks vessel control and time warp.
  * Also SAS an PA were modified to also respect these input locks.
  * Files for building on Linux (using xbuild)
  * Maintained feature parity with your version. 

Overall the code base is quite different in many ways, and I shall continue to maintain my version.

Matthew.