Fixed #22328 -- Added --exclude option to compilemessages and makemessages.
Sycned .hginore with .gitignore.
Updated doc links to point to Python 3 documentation
Specified 'csv and unicode' note as Python 2 only
Fixed #3214 -- Stopped parsing SQL with regex.

Avoided introducing a new regex-based SQL splitter in the migrations
framework, before we're bound by backwards compatibility.

Adapted this change to the legacy "initial SQL data" feature, even
though it's already deprecated, in order to facilitate the transition
to migrations.

sqlparse becomes mandatory for RunSQL on some databases (all but
PostgreSQL). There's no API to provide a single statement and tell
Django not to attempt splitting. Since we have a more robust splitting
implementation, that seems like a good tradeoff. It's easier to add a
new keyword argument later if necessary than to remove one.

Many people contributed to both tickets, thank you all, and especially
Claude for the review.

Refs #22401.
Fix many many typos in comments throughout the codebase
Documented django.setup().

Thanks Eric Holscher and Tim Graham for the review.