[dmd-internals] type inconsistency in the source code

[mrmocool at gmx.de]

> Sure, the names used in dmd aren't particularly consistent... but do
> you really want to break every open pull request?

Hmm indeed a problem. Maybe one could only change those occurrences that  
aren't changed in any pull request.
But in the end most of them are rather small changes that should be  
trivial to rebase.

I also have a hunch that these types aren't used that much inside of  
methods, but rather as class member types or function return types.
Most pull requests don't touch these.