* Refactored some parts of WadNamespaceIterator, added operators to WadIterator.
* Added new WadChainIterator and replaced most ad hoc hashchain iterations with it.
* Removed deprecated global W_GetLumpNameChain.

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2422 86ba831e-150c-0410-ab35-e06eaae15ed9