add error to setup if ptr NULL
return on method errors before crash can happen

also remove unnecessary spaces and endl from messages (ofLog takes care
of this for us)
change ofVec3f types for ofPoint for getWindow____
add getWindowPosition to WindowManager
add getWindowShape to WindowManager
add getScreenSize to WindowManager
cleanup trailing whitespace
regroup window getter/setters
re-order methods to reflect implementation file
add getWindowMode to WindowManager
don’t set focusWindow on push/popWindow
use ofNotifyMouseMoved for all windows

otherwise ofGetMouseX/Y don’t work within push/pop
calls
use macro for window manager error
fix getWindowSize to actually return
add push/pop window to WindowManager
update example with push/pop