Sparse updates

This help test those cases.

Conflicts:
	theano/sparse/tests/test_basic.py

Doc how to make an sparse op

FIX: Example code from tutorial page fails with conversion error

I updated the test to check that. Other place where we talk about remove0 was telling that it just remove 0.

Add documentation about the fct csm_data, csm_indices, csm_indptr, csm_shape, csm_properties and theano.sparse.tests.test_basic.sparse_random_inputs.

This help test those cases.

fix gh-1493 tutorial example that use undefined variable.

Fix exception/segfault newly introduced in gpujoin.

use absolute reference for abs_

For some reason this was failing before

http://deeplearning.net/software/theano/tutorial/examples.html fails with
conversion error, this change fix the problem.

SymPyCCode op

Change grad function name to "grad", not "prime"

Change y**2 test to y**3

Backport to python 2.4

Tests adv sub