Harald JOHNSEN:

Harald JOHNSEN:

- shadow volume vertex are now shared, using DrawElements instead of repeated
  calls to glVertex, this can improve performance on some systems.
- added a rendering path that use the alpha channel instead of the stencill
  buffer.
- releasing memory when tiles objects are destroyed
- objects sub parts will not cast shadows if their name begins with "noshadow"
  or if they are in a <noshadow> animation

- bbcache.cxx :
   don't ask for a 32 bits context when the primary context is only 16 bits

- RenderTexture.cpp :
   corrected a crash when asking for a second rendering context
   on win32 and extensions not being supported

- model.cxx, animation.cxx :
   added a <noshadow> animation, added an animation type needed by the shadow
   code.