use __slots__ in AttrDict

We expect to be allocating a bunch of these, so might as well save some space.
add examples/schema-reserved-words.py

This program checks for words or syntax in schema names that collide with names
used by pybcf.
examples/schema.py: fix help text
add examples/support-bundle.py

This program generates and downloads a support bundle.
add support for BigTap
examples/schema.py: add support for BigTap
add examples/bigtap-hostdiff.py

This script outputs the differences in the set of tracked hosts compared to the
previous run. It's intended to be used in a cron job, where cron will send you
an email if it outputs anything.
merge.