- expr add string: don't call valueOf if the argument is already a
string
- inside String.java, if it called it's own function 'length()', NameNode
didn't generate code, fixed that in NameNode:checkType

Fixed some minor issues with arrays. Can't test yet. Need to wait till merging name node changes and fixing .length

Changed methodInvoke and methodNode so that object is pushed on stack after parameters. Fixed a minor issue