Change the way to initialize Quad & add .svn for gitignore

Add initVertexData function for initializing mVertexData instead of creating it in constructor.
Having this will open the opportunity to change the way to initialize
mVertexData by overriding the function. It is useful when creating a tile like or
particle like quad. For an example, we could use a global vertex data
instead of creating a new one for every quad which makes it faster and
lighter with less effort.

Add .svn to .gitignore
For people who uses svn with git as version control.