Add scraper for Armed Services Board of Contract Appeals

Also includes a complete backscraper.
Speed up 40% by using regex to filter invalid XML chars.

A regular expression to filter invalid XML characters
is many times faster than calling a Python function
for each character.
Add scraper for the Navy-Marine Corps Court of Criminal Appeals

Includes a full backscraper.
Add scraper for Air Force Court of Criminal Appeals

Includes a full backscraper.
Cleanup and tweaks to @janderse's asbca scraper.
Cleanup and tweaks to @janderse's afcca scraper.
Cleanup and tweaks to @janderse's nmcca scraper.
Speeds up the elimination of evil characters in XML.
Formating Tweaks