Fixed test-suite error caused by nosetests trying to run a method that was not intended to be a test by itself

Removed recently added extra argument convert_as_array to TensorType.values_eq, since it is not needed as Pascal pointed out

Fixed crash introduced in fdc11984cb9d when using e.g. a list as input to a theano function instead of an ndarray

Fixed crash when adding to C cache a Composite Op created before adding / modifying some config options

- Added some doc about the identity, commutative and associative fields
- Fixed crash in filter function when using NaN values

sger accumulates into an output buffer, so if a c-continuous output
memory buffer was used several times, the result was incorrect.

If scan receives memory in the output storage map it uses it. Now if you run
truncated BPTT, you do not loop over the entire sequence, and you should
return 0 for all the entries you don not visit. I used to assume that the
data I allocate does that ( because I used to allocate it using zeros), but
now if data is provided I did not check if those values are actually 0s.

Before, scan used to add another layer of abstraction between constants and
the inner function, so even if you would give as a non sequence a constant
the inner function will treat it like a normal theano variable stopping
certain optimizations to happen.

It was added by James in f062502a097c but he does not remember why it was
there. It looks like it was never used.