ENH: Do kwsys testing as part of cmake testing, command line arguments are not experimental and add simple test for systemtools

ENH: Adding SGI hash_map and hash_set implementation ported from STL to KWSys.  This also adds try-compiles for KWSYS_STL_HAS_ALLOCATOR_REBIND, KWSYS_CXX_HAS_FULL_SPECIALIZATION, KWSYS_CXX_HAS_MEMBER_TEMPLATES, and KWSYS_CXX_HAS_NULL_TEMPLATE_ARGS.

ENH: Added proper namespaced version of KWSYS_STL_STRING_ISTREAM_DEFINED, KWSYS_STL_STRING_OSTREAM_DEFINED, and _STL_STRING_NEQ_CHAR_DEFINED macros.

ENH: Added istream and ostream operators for stl string in KWSys when using old streams that do not provide them.

ENH: SplitPath now supports slashes in both directions in the input path but still produces forward slashes in the root component.

ENH: Added istream and ostream operators for stl string when using old streams that do not provide them.

ENH: Adding SharedForward C header to help create forwarding executables on UNIX systems that configure the shared library runtime search path and then replace themselves with the real executable.  This is useful to create binary distributions that work from any extracted location even with shared libraries.

ENH: Re-implemented CollapseFullPath to not need to change directories.  Operation is now fully string based.

ENH: Added "ostringstream(const kwsys_stl::string& s)" and "void str(const kwsys_stl::string& s)" compatibility methods.