Move ivar declarations to their class extensions

This is really just to make the code style more similar to the TextMate source.
TMDNibController: Use properties
TMDIncrementalPopUpMenu: Use properties
Delete Dialog2_Prefix.pch on disk

We removed the Xcode project (63887858021f043c1979efa20d9c4e88c0e8db1a), which contained the original build system. Since we now use the custom build system in the TextMate source (along with it's precompiled headers), let's delete it.
Remove unneccesary headers

These are already included as precomiled headers when building from within TextMate (which is currently the only supported build system).
Don't link again Carbon

The last use of Carbon was deleted in d879791c606dca908fe423c1e839c6ba92f9217c.