Upate documentation files. First Pass.
Merge pull request #265 from mono/master

Upate documentation files. First Pass.
Added stream loading of PlistDocument instances.
Fix for label width adjustments for multi-line labels.
Merge pull request #266 from totallyevil/STREAM_LOADING_PLIST

Added stream loading of PlistDocument instances.
Merge pull request #267 from totallyevil/LABEL_WIDTH_FIX

Fix for label width adjustments for multi-line labels.
Documentation Pass 2
Documentation Pass 3 for Summary description
Documentation Pass 4.  Messed up remarks with last commit.
Merge pull request #269 from mono/master

Documentation Pass 2 and Pass 3
Rename README.txt to REAMDE.md so that we can format the text.
Merge branch 'master' of https://github.com/mono/cocos2d-xna
Merge remote-tracking branch 'upstream/master'
Still more to do but getting the formatting started.
#268 - Fix for NRE in b2Joint construction.
Add Download section and some cleanup
Add templates section
Add Getting Started section
Add Getting Started section
Add Getting Started section