Branch 'Horseshoe' (#3)
Missing icons
Allow REXX to be make'd on other platforms.

The modified Makefile are somehow wierd and need to be fixed.
Forgot dectests...
Reworked the Makefiles
Makefile revamp to be enable windouze compilation (using mingw-w64)
Allow launching REXX via implicit intent.
delbuf() is microzoft specific...
Finishing 'horseshoe'