I made a registration system that allow all Theano Type to tell if they allow OutputGuard to generate c code for them. This fix the dependency on sandbox code in theano/compile/mode.py file. This make it a better fix then what was done for SparseType.

Added test.

Fix extract diag

Fix sparse dot

Composite fixes

But they cause a mysterious bug in test_gpu_fusion on my mac in which the second
of cases 2 and 3 (any order) fails to update the result buffer. I tried but
failed to fix it so far.

Adding tag traces is expensive. This PR disables adding tag traces during the
optimization process itself, which is anyway not the point of tag traces. This
saves 10 seconds of compilation on a graph I'm working with that ends up with
about 240 nodes.

Removed debug print that crept in

Typos

Better error msg.

Fix
Looks fine, mostly it is pep8 compatibility fixes.
Razvan

config flag for max_use_ratio in Equilibrium optimizer