Remove u_fudge

[adroitwhiz]

Proposed Changes

This PR removes the u_fudge uniform from the GLSL code and all renderer code that sets uniforms.

Reason for Changes

u_fudge was first used in the testing playground as a way to debug effects. By hooking it up to a slider, it could control an arbitrary shader component--this was useful for testing the shaders.

Now, the "fudge" slider in the playground does not control u_fudge, but can instead set many other properties of the playground's test drawable, including every effect.

Every call to gl.uniform[*] adds a small performance cost, so we want to avoid setting unnecessary uniforms.

[thisandagain]

/cc @cwillisf @kchadha @mzgoddard

[cwillisf]

😄