Very basic blocks support

Before this patch:
```objective-c
- (void)enumerateObjectsUsingBlock:(id)arg1;
```

After this patch:
```objective-c
typedef void (^CDUnknownBlockType)(void); // return type and parameters are unknown

- (void)enumerateObjectsUsingBlock:(CDUnknownBlockType)arg1;
```

At least it is clear that the parameter is a block.

I quickly hacked that, maybe there is a better way to do it.