added arccos

Deprecated cache entries now trigger a warning

Most people should have updated their local cache by now. Making it a
warning will ensure we notice if for some reason a bug generates new
invalid cache entries.

Misc style fixes in op.py

Functions for clean interactive debugger code

interactive debugger

Deprecated tensor.shared (renamed tensor._shared)

STY: various blas/test_blas fixes

Most of the time people who use tensor.shared do it because they mix it up
with theano.shared. By renaming it with a leading underscore, this confusion
should disappear.

By the way this commit also changes a few calls in Theano code from
tensor.shared to theano.shared, when I thought calling tensor.shared was not
intentional.

Fix missing pydot (tests/error message)

Dot22 complex still w pep8 errors but Fred's busy.

fixed cifar example.

Tensor cast error is clearer and has helpful hint.

To avoid confusion, 'array' usually refers to numeric (numpy) data,
while 'tensor' often refers to symbolic (theano) objects.

Switched order of exception arguments to first say that there is a bad
input in some position, before explaining why it is bad.

Added a 'size' attribute to tensors