Tweaked CMake build and added some features.

- Tweaked cmake to build only the bare minimum.
- Added tutorial folder to get beginners started with AGG and help them
survive with the poor AGG documentation.

(But wow!!! For such an elaborate software, AGG code is amazingly terse
and efficient!)
Merge davidok8/master

Conflicts:
	.gitignore
	agg-2.4/CMakeLists.txt
	agg-2.4/src/CMakeLists.txt