Ensure that texture object is properly created before using it.

As glGen*() only reserves object name without creating it, it must be
ensured that the object is created before calling functions which expect
already created object (such as glObjectLabel() or glBindTextures()).
Allows me to remove quite a lot hacks in the tests.
Ensure that buffer object is properly created before using it.
Ensure that the framebuffer object is properly created before using it.
Ensure that the mesh object is properly created before using it.
Ensure that the renderbuffer object is properly created before using it.
Proper state tracking also in texture-multi-bind.
Fix Buffer move construction/assignment on NaCl.
Text: fix performance warning in test.