Fixed shared context crash on windows.
Fixed mouse button setting in ofxFensterManager

When notifying mouse events, there was no button initialization, so in user app button wont be recognized properly.
Merge branch 'master' of github.com:blazm/ofxFenster into blazm-master

Conflicts:
	src/ofxFenster.cpp
	src/ofxFensterManager.cpp
Merge branch 'blazm-master'