Make copyExprOps static.
A version of Expr that should work, but doesn't for some reason.

There appears to be a problem with 2D arrays of constant memory.
No matter what configuration I give, the constant ops array is always
blank. Going to try with a 1D array.
A fully working kernel, just one data corruption between calls.

Need to investigate this more with a different compiler.
Fix header import of VapourSynth.h in VSScript.h
Finally, a fully working Expr.

Should handle multiple instances, interations, etc.
Fixed error checking in Expr for offset.
Merge branch 'fix_expr' into cuda