Some other DAoC related fixes to XML.

Made DLL creation optional and added a "Release - DLL" configuration.  The Release configuration creates a static library.

Moved all generated files to gen sub directory.
Renamed some generated files.

Updated license text in remaining files.  Short text in all files except niflib.h, and year updated to 2006.

Noticed that I had forgot to include NiObject.cpp in my last commit... unfortunately I've already started splitting off classes into their own files so that's included in this commit as well.
I also noticed that I never implemented the member functions of Ref!  I still haven't, but I was just surprised it's been compiling without complaint.

Got rid of globals for good measure.

Moved things around and updated xml_extract.h so that everything compiles again.  Other than NIF_Blocks.h/cpp which will be removed in the future, of course.

Implemented some of the object hierarchy the new way in nif_objects.h and started updating niflib.cpp.

Removed interfaces and moved documentation to real classes.  NIF_Blocks.cpp and niflib.cpp no longer compile.

Begun work on the new type of Attributes which store pointers to their data rather than the data itself.  Moved some code to new files to fix problems with cross-includes.
Need to decide what to do about TexSource, a struct in the external interface that should have a link in it.

Created Link, LinkGroup, CrossRef, and CrossRefGroup classes which automate the process of adding and removing links and cross references to a block.  Had to put them in Nif_Blocks to avoid including that file in NIF_IO.

Removed split-tree functions from public interface.
Restored WriteFileGroup.

Added SplitKfTree and SplitNifTree functions to the interface. SplitNifTree is implemented for Morrowind only (copied code from old WriteNifTree function), SplitKfTree is not implemented at all. These two functions replace WriteFileGroup.

Updated MergeNifTrees to handle some cross references (skin blocks).  Other blocks with cross references can be added by overloading the ABlock::ReassignCrossRefs function.

MergeActions: read NIF file and all KF files (TODO: merge them as well).

Added documentation to IControllerSequence.

Brought NiControllerSequence up to date with DocSys, but commented out interface functions for later implementation.

Block implementation is current with DocSys again.

Small changes to constness of some functions.