Fix cmake build script for compiling examples

  * Almost there for production usage...
Temporarily remove the compiling of json functionality from library

json_spirit has not been very kind in spirit of cross-platform, so... in
interest of keeping consistency with the platforms, until I decide on a
replacement for it!
Introduce using supplied third-party libraries for cmake script

	* Remove third-party from ignore list
	* Add third-party libraries & headers for OS X to third-party dir
	* Rename EXTERNAL_HEADERS_DIR to EXTERNAL_DEPS_DIR
	* Rename cmake vars: SDL_INCLUDE_DIR to SDL2_INCLUDE_DIR and
SDL_LIBRARY to SDL2_LIBRARY
	* Use EXTERNAL_DEPS_DIR in place of hard-coded 'third-party' in all
applicable file paths
	* Add third-party libraries & headers for OS X to cmake script
Additional clean up (fixing this and that) for cmake build script

- nomlib library
	* Comment the install library line for Windows platform; this is for
future consideration...
	* Move the source_group for both header & source files outside of
conditional platforms statement and hopefully fix the FILES glob for
header file inclusion

- nomlib examples
	* Fix compile err for non-Windows platforms by forgetting to separate
the link_libraries line
	* Introduce source groups for example source & header files
	* Remove the conditional platform statements; this has been verified
on Windows to be OK
Remove extlibs directory (we now use third-party directory)
Implement the setPath method
Add examples folder to project