add GradClip op

[FIX] Add define for PyInt_FromSize_t for Python3.

Multi-GPU scan fixes

Document steps required to get Theano up-and-running on Ubuntu LTS (optimized)

Change default platform to something that don't change when it isn't nee...

Fix infer_shape user warning for not implemented case

Fix compilation crash with cudnn on python3

Sparse slice with step

Note: the setup develop call is required IFF there is a change
to the set of command-line (or other) entry points for the package,
but it is not required for *most* changes.

abergeron requests removal of it, so I'm removing it.

Instead of putting the "if you work harder you can get better performance"
note before the code, make the code the first thing you see and only
note that you could do it another way in the performance testing section.

Also switches to code-blocks throughout.

Adds note that the openblas thread limit note seems to be outdated,
the section above notes that we should be linked to multithreaded
blas already, and testing seems to suggest we are.

Includes link in case users aren't familiar with the tool.

doc/install.txt and doc/introduction.txt: Some spelling corrections

Fix truncated gpu dev pointer on windows 64 bits.

Fixed 'comparison with None' warnings

Do not make Theano cache code delete the lock directory. This fix proble...

Disable Theano gc in scan by default.

This do what gh-2385 should have done.

Do not make Theano cache code delete the lock directory. This fix problems happening in the daily buildbot due to concurrent Theano process.

fix test in FAST_COMPILE