[YAGGLER/SHADER]: removed the is_link() method and replaced it with has_ownership(). Some speed improvement in uniforms.
[YAGGLER/TEXTURE]: removed the is_link() method and replaced it with has_ownership().
[YAGGLER/GEOM]: removed the is_link() method and replaced it with has_ownership().
[YAGGLER/INIT]: removed a warning when YAGGLER_NO_MESSAGES is defined