Autowrap implementation for CCLabelBMFont

Here is the implementation of autowrap for CCLabelBMFont. I haven't done massive amounts of testing on this implementation but most of the common bugs are fixed. Text cases are in LabelTest, it runs on iPad Simulator at least. Most likely iPhone will be a bit messed up because the font was large and some numbers are hard coded in the test case, the implementation still works. It should also work on Mac.

The implementation goes through the characters one by one and inserts/replaces the line changing characters where needed and then creates sprites as before. Added benefit for counting the characters beforehand is that now CCTextAlignment can be used for CCLabelBMFont as well. Only one new function needs to be added to the API:

+(id) labelWithString:(NSString *)string width:(int)width alignment:(CCTextAlignment)alignment fntFile:(NSString *)fntFile

Please check this out and see if it can be used. In case you want me to develop it further that's fine too.