Add elemwise `conj` to `sparse`.

Flake8 scalar

Opt: Alloc(Alloc(...),...) -> Alloc(...) #1902

OpFromGraph.connection_pattern()

Flake8 sparse

Conflicts:
	theano/tensor/tests/test_opt.py

opt support arbitary dim broadcasting

proper tests

better alloc

remove conficts

pep8 fix

Added Help! section to docs index page

- Moved latest release info to top of news section.
- Added paragraph about searching for help before asking fresh.
Also made a few small changes for style.

add docs for NanGuardMode