Improved interface for autocompleteda (now can take account of
generators with same idempotents). Some refactoring of arcslideda and
arcslidedatest to use the new interface.
Solving a system of equations over F2 using the cancellation lemma.

Incorporated an improvement to simplifyComplex - avoid cancelling
arrows whose degree has increased too much between when it is added
and when it is about to be cancelled.

Corrected a bug in CobarAlgebra.multiply.
Implemented DA tensor DD using delta() and deltaPrefix in DA. Used
this to verify that the DA structure produced in arcslideda.py agrees
with the DD structure produced in arcslide.py when tensored with the
identity DD bimodule (it is not necessary in the overslide case, but
appears to work there also).
Type DA for anti-braid resolution. The middle case is very complicated
- two different solutions are placed in separate files. Testing shows
arrows with 4 algebra inputs are really needed.