ENH: Added KWSYSPE_DEBUG macro to print debugging trace information.  Added TODO comment explaining why process execution can still hang when a grandchild keeps the output pipes open.

COMP: Fix warning about binding reference-to-non-const to an rvalue on VS6.  It does not seem to be doing the proper auto_ptr_ref conversions.  Instead use the const_cast work-around on this platform.

STYLE: Fixed documentation of how to produce forwarding executables for multi-configuration builds with CMAKE_INTDIR.

BUG: When a "wrong argument" was detected, we call the WrongArgument handler. If the handler returns success, the argument parsing should continue. Currently, it was stopping parsing immediately after the wrong argument was processed, irrespective of the WrongArgument handler status. Fixed that.

BUG: FileIsDirectory would remove the trailing '/' even when the path is indeed the root i.e. '/'. Hence the test would be incorrect for root directory. Fixed that.