New command line option support.

Clutter now features a few useful command line options. These can be accessed via use of any program linking to Clutter. They shouldn't usually be needed, Clutter will always try and do the right thing. The options are there to work around buggy video drivers or help with debuging and optimisation.

For a full list of options pass '--help-clutter' on the command line. Some of the most useful options are;

--clutter-debug=FLAGS turns on verbose debugging messages. This can be 'all' or narrowed down to a particular area of code via setting FLAGS to one or many (comma seperated), of misc, actor, texture, event, paint, gl, alpha, behaviour, pango. Note, this option can be completely compiled out for very size critical builds.

--clutter-vblank=METHOD overides clutters automatic selection of which vblank syncing mechasim use. Valid values are 'none' (really only of use if you have a buggy driver and experience a very low frame rate or want high performance and dont care about choppy tearing effects), 'glx' (The preffered mechanism) and 'dri' (kind of hacky and Linux only - but only option for some drivers). You can also set the mechanism used via the CLUTTER_VBLANK env var.

--clutter-show-fps displays the frames per second clutter is currently rendering at.