Razer Hydra integration
Change ShapeBase to only test if available meshes

The ShapeBase class tests if all of its meshes are hidden and if so,
then it doesn't render during that frame.  However, if there are no
meshes in the ShapeBase and only nodes then rendering is also skipped.
Unfortunately, this also skips the rendering of any mounted images.
This change allows for a mesh-less skeleton to render any mounted
images.
Merge pull request #236 from DavidWyand-GG/HiddenMesh

Change ShapeBase to only test if available meshes
Compile Bullet library under Windows

For some reason the Bullet physics library's project file was not being
included in the solution when the bullet module was added.  This change
makes sure that when you want to use Bullet, it will correctly be added
by the Project Generator.
Merge pull request #237 from DavidWyand-GG/BulletBuilding

Compile Bullet library under Windows
Merge pull request #234 from DavidWyand-GG/RazerHydraWork

Razer Hydra integration