Fixing parsing of Facebook SDK. 

* Adding support for multiline comments in Attribute generator:
```
@"long"
@"string"

@"long"
"long"
"string"

@"very \
long \
string"
```
* Fixing parsing methods with attributes, like:
```
- (void)method __attribute__(...);
- (void)method NS_SOME_ATTR_MACRO;
```