migrate to -[NSArray firstObject] for safety

Using -[NSArray firstObject] will return nil on an empty array while -[NSArray objectAtIndex:0] will throw an NSRangeException.
Added gl::windowToWorldCoord() and gl::worldToWindowCoord() utility functions.
Added a test application for gl::windowToObjectCoord() et. al.
Made using gl::windowToObjectCoord() easier...
...by allowing the user to specify the model matrix. That way, you don't have to set it as the active model matrix. It also allows us to inline gl::windowToWorldCoord(). Updated the test application so it exercises all functions.
Changed ivec2 to vec2. Removed icons.
Merge branch 'firstobject' of github.com:pizthewiz/Cinder into pizthewiz-firstobject

Conflicts:
	src/cinder/app/AppImplCocoaBasic.mm
added some nil firstObject checks
Merge pull request #593 from cinder/objc_firstObject

Obj-c firstObject
Merge pull request #544 from paulhoux/window-to-world

Added gl::windowToWorldCoord() and gl::worldToWindowCoord() functions.
fix iosTestApp build on sim
using CI_LOG_V in main desktop and iOS test apps as it is much easier to track down where what is coming from this way.
Merge branch 'tests_logging' into glNext

Conflicts:
	test/iosAppTest/xcode/iosAppTest.xcodeproj/project.pbxproj
	test/windowTest/src/windowTestApp.cpp
fixes for tests logging updates on glNext branch