VectorStorm now drops its framerate when its window is hidden.

Previously, did it when the window lost focus.

Also, added log messages for the other SDL window events (which look
like they duplicate the functionality of other events?  But at least
this will help me figure out exactly when which events are sent)

TODO:  Should this be configurable, instead of hardcoded behaviour?
Adds operator* for container iterator types which were missing it.
Add vsFloatImage.  Like vsImage, but stores data as full floats.

If turned into a GPU texture, uses half-floats.
Fix non-uniform scaling on 2D transforms
Merge branch 'master' into custom_uniforms