Fix copy-paste error in docs.

More aliases, reordered.

Scan reintroduced benchmark

Make negative values for gpuarray.preallocate disable the allocation cache completely.

Add opt Elemwise[EQ](Subtensor(Shape(x)), -N) -> Elemwise[zeros](X) that work around this comment by removing the re-inserted scan: https://github.com/Theano/Theano/pull/4356/files#r61901454

This will force a recompile of everything and get rid of old modules
that refer to the previous locations of the Ops, which causes a
warning when they are reloaded.

cache completely.

Move new GPU backend out of sandbox

[CRASH,REGRESSION] Fix crash gpufft