Yet another size fix

Minor stuff

enable_sparse is indeed a Boolean

Fix composite new inputs

It happen in a particular execution order of this optimization and the
element-wise fusion optimization when upcasting some inputs to
float32 (to compute them on the gpu).
(Frederic B., reported by Sander Dieleman)

Fix for win64

New interface for scan

Gpuconv

fixed bug in min_informative_str

Fix syntax error, remove unused import.

This is temporary, as we should remove NONE_CODE ultimately.