ModalOverlay to show images as a translucent full screen overlay
Merge remote-tracking branch 'oswaldo/master'

Conflicts:
	IrregularVerbs.xcodeproj/project.pbxproj
	IrregularVerbs/RootTestViewController.m
Removed helpView and tapRecognizer
Help screens up&running. testScreenHelp bimaps renamed to conform Apple criteria. firstTime flag individualized for each help screen
Device Height file loading isolated on a new UIImage cathegory
Minor bug in UIImage+H568... if you compute a new image name, better use it ;-)
Merge pull request #66 from rbarbera/master

ModalOverlay to show help screens