Update goAppDelegate.m

Fixed memory leak in addToFromPM:, changeMoveIndexed: --- 
changeMoveIndexed: generally when you return an object, it should be autoreleased so the caller does not have to worry about a retain cylce/leak.
addToFromPM: the MovePlayed object created on line 35 has a retain count of 1 when created, then gets retained again by the array _myPlayedMoves when you add it. This creates a memory leak because there is one retain that never gets released (the one to goAppDelegate)  

Changed title of addToFromPM (objective-c style favors verbosity over conciseness)
added OPEN sgf support
Merge pull request #2 from nielubowicz/master

Update goAppDelegate.m
fixed calling openPanel twice issue
Update README.md
Update License
Merge pull request #3 from Nadohs/openSGF

Open sgf