NewVersion_17thSep11

Several improvements are implemented in this version of 17th September:

• modified keyboard driver for improved ALT-key support
• added an Alt-comma key combination to switch temporarily to text mode and back refreshing the screen. This allows debugging with GDB.
• wrote an event-driven mouse driver to improve performance
• screen driver will redirect STDOUT to the NUL device when enabling SVGA mode. Text output to STDOUT did corrupt the SVGA display.
• added the NANOSCR environment variable to set the screen resolution and color mode
• added a default directory in the FLTK editor example
• added missing image to libimages.a so the mdemo.c example will compile