Fixed OSX 10.8 build errors

It seems that <OpenGL/glu.h> is missing from the
10.8 SDK, so falling back to 10.7 SDK.
Example 01 ported to iOS
comments to explain 'what is glState?'
Add Default images
article 02: Texture port to iOS
03 Matrices ported to iOS
WASD gestures working
Article 04 ported for iOS
added iOS_main.h include statement
Renaming light "color" to "intensities"
Device Accelerometer to move the camera up.down
Merge remote-tracking branch 'upstream/master'
port to iOS
Updating .gitignore for iOS
Added missing Xcode files
Update README
Merge remote-tracking branch 'upstream/master'
Changing "cosAngleOfIncidence" to "brightness"
iOS port of articles 01 - 05
Removed uneccessary Xcode files