Changing "cosAngleOfIncidence" to "brightness"
iOS port of articles 01 - 05
Removed uneccessary Xcode files
Added Sidharth to credits
Updated gitignore
Making lighting frag shader easier to understand
Final code for article 06
Brightness calc look more like formula
 Fixed some type conversion warnings from VS
Article 06 done for windows
Updated README for article 06
Ported tutorial 06 for linux.
Merge branch 'master' of git://github.com/tomdalling/opengl-series
Article 06 Ported to iOS