Fix case where redefining uniforms caused state errors
Fix case where redefining uniforms caused state errors

We were getting errors when adding or removing uniforms in some cases.
This change swaps out the defvar/defparameter code in favor of having
the recompile function handling the resetting of the state variable.

I'm not 100% happy with this, it feels data-racy but it seems to be
working well so will be good enough for this release

cbaggers/cepl