first draft of SymPyCCode op
add remove utility function
import remove
add c_headers to SymPyCCode op
add SymPyCCode.grad
protect sympy tests if no sympy
skip sympy tests with skiptest
fix typo on skiptest
small edits to SympyCCode and test

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

Change y**2 test to y**3
Merge pull request #1486 from mrocklin/sympy-ccode-op

SymPyCCode op
use absolute reference for abs_

For some reason this was failing before
compile and run test_norm function
Merge pull request #1490 from mrocklin/abs_

use absolute reference for abs_
Add paramter unsorted_indices and explicit_zero to sparse_random_inputs()

This help test those cases.
fix Theano tutorial section type.
Add documentation about the fct csm_data, csm_indices, csm_indptr, csm_shape, csm_properties and theano.sparse.tests.test_basic.sparse_random_inputs.
Document in Theano tutorial how to make a sparse op.
Updated user warning to tell where we have the OrderedDict implemented.
Remove comment that is wrong. The remove0 op don't sort the indices.

I updated the test to check that. Other place where we talk about remove0 was telling that it just remove 0.
Add a note about logout/restart in the installation guide.