Updated trees and better depth of field effect.

Leaves were made to be translucent and double sided and the leaf texture was edited to give trees a more natural look.
I made the DOF effect work much better but work still needs to be done to clean up the old code and perfect the new effect.
I'm not sure if the comments in my code would be considered excessive but that is just how I like it to reduce the stress of having to figure out things again if I don't get the time to work on this project regularly.
This would be great as a one-line javadoc comment, /** comment */

Or the three line format, for that sake, not sure if we prefer either. I like the one liner for short stuff.

I guess we can't use javadoc in .glsl files though, alas! :-)