Shaders: test compilation of *Vector shaders.
Shaders: test compilation of Flat and VertexColor shaders.
Shaders: test compilation of MeshVisualizer shader.
SceneGraph: shorten lengthy test names to preserve 80-column ctest output.

As we now have 100 tests (yay!), ctest needs three more characters to
display the progress, thus we need to shorten the long test names a bit
more. Should suffice for a long time, I'm not planning to have >999
tests :-)
Shaders: test compilation of Phong shader.

Currently fails for some combinations.
Shaders: fix Phong shader compilation for more than one texture.
Shaders: fix compilation of textured Phong shader on OpenGL ES.