jessedc/JCTiledScrollView — pull request #29 by yichizhang (2014-12-18 13:45:44+00:00)
Title: Fixed two bugs

1. Sometimes the scroll view freezes; the error message says `+[CATransaction synchronize] called within transaction.`
The reason was, previous code could cause something like this to happen
```
[CATransaction begin];
...
[CATransaction begin];
...
[CATransaction commit];
...
[CATransaction commit];
```

2. Fixed the error of trying to add a nil object to NSMutableSet *_visibleAnnotations
Added nil checks for objects to be added to that mutable set

I haven't really changed a lot of code; but I think I turned on CLang Auto Formatting so it's going crazy