Finish renaming ObjC declaration actions.
Add comments.
Switch to new indentation style for the Action class. Since many actions take many arguments, the new style will...
- make it easier to add/remove arguments without messing up the indentation...
- make it easier to add comments to each argument (see ActOnMethodDeclaration for an example)...
- in general, just makes it easier to see what is being passed.

The rest of Actions will be converted "lazily"...there is no immediate need to hack all the existing methods.

llvm-svn: 42587