Rationale: this way it can be optimized with the same machinery that currently
targets dot.

I will add back a modified version of Outer as sandbox/blas_ger.py. In future,
we should have a GER Op in blas.py, with a scipy and/or c implementation that
uses BLAS's sger/dger/cger/zger functions.

It's a shortcut to cast. It's used in the GEMM unittests.

set_subtensor.

This was the cause of the 3 failing test in scan. I also revised the entire
optimization, writing a bit more comments/

variables and some other cosmetic changes.

* * *
More informative error message

ensure they don't belong to a different env.

Also update the documentation.

The scope is to make the computational graph more readable, and to move
constants in the inner graph, allowing constant folding in the inner graph
to do its job (performance).

obtain some outputs/or other node.

In order for scan to identify which of the inner outputs is the stopping
condition I use this dummy class to wrap my condition in it.

Look for conditions that the user might provide ( if scan is to terminate on
a condition ). This feature will be later used the conditional terminating
scan.

One thing that I've tried is to avoid importing cuda.