fixed bug where ifelse rejected sparse types

Scan grad computation fixed

Cvm runs testsuite

improved doc for get_debug_values

removed extraneous space

Fixed crash when theano.version does not exist

This is the case for instance when someone directly uses the git
repository without running setup.py.

Feature: advanced inc subtensor grad

More readable error when compilation fails

improved doc for R_op
it all looks good. There is one line that I think does not respect PEP8 convention but I'll fix it in another pull request

Include the theano version in the compiledir.

added ability to use debug_assert without a message argument

fixed a bug where get_debug_values returns tuple(val) rather than val in

the case where it is fetching the value of only one variable

* No more forgetting to clear the cache!
* No more collisions when running multiple theano versions at once!

fixed error handling and doc for ifelse

(there was a problem that would reject a pair of branches
where one was shared and the other was not, regardless of
whether they had the same type)

This commit introduces 'accept_var_updates' that the VM_Linker uses to get
update expressions from the FunctionMaker class.  The previous code didn't
work right with ProfileMode, as triggered by the test_modes unit test.

Minor stuff

Also added a test to theano/tensor/test/test_inc_subtensor.py, but I am
unsure yet if it actually belongs there.