Beginnings of the new Expr filter. Completely untested.
Added cuda call to Expr filter, fixed a linking issue (Expr is c++, not c).
Added some debugging options, fixed an issue in stride, but still got a mem error.
Fully working Expr filter!

Needs some optimizations and tweaking still, but it certainly works!
Dammit, it's not working again and I don't konw why.

This should work, but doesn't for some strange reason.
Fixed previous issues.

This was due to the use of the mulhi and mul24 instructions.
They can probably be used correctly but for now we will just get by with
a normal add and multiply.

This was causing issues in other filters as well, such as LUT,
     MaskedMerge, and Merge.

Now, luckily, all filters work, including Expr.

The use of the mul* instructions will need to be investigated in the
future.