Finish and integrate NeL 3D decal branch

[kaetemi]

Branch feature/decals merges in a snapshot from 2007 July 5 of a new decal implementation for NeL which may replace the CDecal in the Ryzom client used for Ryzom Ring.

This implementation was done by an intern of Gameforge France, but is incomplete, has not been tested exhaustively, and is not integrated in the Ryzom client yet.

The merged snapshot is not the last revision of the original code, but should be largely complete. The last revision was lost by Winch Gate, as they did not keep any backups of the original CVS repository.

Details on the implementation, pseudo-code of the final implementation, and reference on what else may be missing from the code we do have, can be found in the intern's report.

fr_training_3d_decal.pdf

If necessary, this feature may be refactored from scratch.