Cleanup RunCOmmand code and move borland one to vtkWin32ProcessExecution, so that it is all in one place... Add timeout option whihc does not work yet, but it should not produce warning any more

ENH: Added explicit declarations of some C functions that are hard to get from standard headers in como (www.comeaucomputing.com) strict mode.

ENH: Added support to pass the gccxml program location to cable if ITK_GCCXML_EXECUTABLE is set on m_Makefile.

Fix a bug in generator. This one is good: This bug is only present on Windows 98, but since RunCommand did not work, it never showed on the dashboard... In any case commands in Visual studio 6 should be in windows style slashes

     confusions.