Make CompareData give more useful error message
Remove old mode range reference file

Shouldn't have been commit to begin with, was rendered obsolete by
commit 7fc5658
Remove AsClip call from Invoke in ImportScriptAvs

Stupid mistake; forcing the result of Invoke into clip form means any
subsequent calls to AVSValue type checking functions can't be trusted.
Add RunTestAvs function
Add first output tests, for tilew and tileh

Test scripts and reference data forthcoming.
Add scripts and reference data for previous commit