ENH: Adding Shell_Flag_EchoWindows option to setup escapes for arguments to the native echo command in a shell.  This special case is needed to avoid adding quotes when passing text to echo in a native windows shell which does no command line parsing at all.

ENH: Adding tests KWSYS_C_HAS_PTRDIFF_T and KWSYS_C_HAS_SSIZE_T to help ProcessUNIX.c build everywhere without warnings.

ENH: Renamed kwsysPlatformCxxTests to kwsysPlatformTests and generalized it for multiple language tests (C and CXX).

ENH: Added Process_SetPipeNative method to allow user code to override the pipes connected to the child pipeline.

ENH: Re-implemented command line argument shell quoting to support several platforms with one code base.

BUG: Windows_ShellArgument: need to escape if the string contains one of a set of special characters as well as spaces.  Moved test for needing escapes to a separate method kwsysSystemWindowsShellArgumentNeedsEscape.

ENH: Adding 'System' component of C sources to hold system tools written in C.  Moved windows shell command line argument escaping code to kwsysSystem_Windows_ShellArgument and kwsysSystem_Windows_ShellArgumentSize.

ENH: Added KWSYS_SHARED_FORWARD_OPTION_COMMAND option to allow users to replace the command executed.  Extended documentation at top of file.

BUG: When a try-run fails to compile create the run result cache entry with a bogus non-zero return value to avoid running the test again.

BUG: GetLineFromStream should remove carriage return characters to make sure newlines do not get duplicates.

ENH: Separate the notion of a request for LFS and its availability.  Allow user code to block definitions of LFS macros.  Added framework to give error if sys/types.h is included before this header when LFS is requested (currently disabled).

ENH: Exposed pattern->regex API.  Cleaned up and commented implementation of pattern->regex conversion.

BUG: strlen logic was backwards resulting in function body never actually executing... when called with valid strings, it was always doing nothing and returning false... now it works as expected.