[Cmake] FindCygwin.cmake

[Sebastien BARRE]

Last, but not least

  - FindCygwin.cmake : find Cygwin install path, a well as the path to some 
usual commands (RM: rm, MV: mv for the moment)

For these of us that are wondering about this module frenzy: I just want to 
be able to launch a shell script as a custom target, but it appears that 
Microsoft Visual Studio just does not care about your PATH environment var 
! It will use a snapshot that it took when you installed it. Hence, if you 
installed Cygwin, Tcl, Perl, etc *after* Msdev, you will have some nice 
surprises. So let's make sure that even the simplest thing can be found.

Sebastien