- Change the iterator postfix increments to prefix, since that is how they are implemented. Nothing relied on postfix behaviour and prefix is more efficient, so we want to be using them anyway.
- Commented out the decrement operators since they are not yet implemented by the tile iterators. Only the fill painter was using a decrement (under certain circumstances), and that wouldn't have been working.

svn path=/trunk/koffice/; revision=401042