Minor fix in an theano/tensor/blas.py.

First version of file for the release candidate.

Changed argmax dtype from int32 to int64

Refactored GPU install instructions

Also refactored a bit GPU tips, and removed the note about limitation to
4 GPUs (which is not true anymore).

Moved instructions from "Using the GPU" tutorial page to the intallation
instructions.

Added a link from installation instructions to the "Using the GPU"
tutorial.

Minor stuff

Fix argmax grad

Some test fixes

Fixed some tests with compute_test_value = ignore

Now also testing gradient with axis=None (failing as of this commit).

If 'axis' is empty then x.ndim must be equal to zero, and thus we also
have 'axis == range(x.ndim)'.
If x.ndim in non-zero, there is no reason for axis to be empty, so
better not catch this case.

Windows requires pickled files to be opened in binary mode.

Also rewrote file operations to be safer.

Fixed test_lazy.py and test_vm.py

Everything looks fine.

Fixed test_vm.py:TestCallbacks.test_callback_with_ifelse.

Two tests are now failing in test_vm.py

This is safer on 64 bit computers, and remains platform-independent.

fix test in FAST_COMPILE.

change the default of theano.{max,min,argmax,argmin,max_and_argmax} to t...

Changed default compiledir under Windows

Added documentation about newly-added VS files

Fix #12

This option was redundant with config.base_compiledir

A few notes:

* I went ahead and removed theano/misc/hg_version_hook.sh. It
  is not functional now, so I inferred that no one cares about
  it (file a new issue if I'm wrong!). It'll be in the history,
  should we ever want to write a git hook replacement for it.
* I made some minor whitespace fixes, including collapsing the
  unnecessary double-depth try/finally.
* I think that the _minimal_ext_cmd isn't needed, but I left it in.
* Why not do direct substitution into full_version, instead of
  writing code to do Python substitution again? Left it as is for
  now, in case there's a good reason...