Feature - added shared library approach for visual studio users

Use ofxTimeline as a shared library so that:
1. very easy project setup
2. changes to ofxTimeline file structure don't affect your project
3. quicker compile times (only compile ofxTimeline and its dependencies once across all your projects)

check https://github.com/elliotwoods/ofxTimeline/tree/master/ofxTimelineLib for info.