* Added exclusions module with a fully implemented ExclusionsDB that can pull
from multiple sources for different sites.
* Moved CopyvioCheckResult to its own module, to be imported by __init__.
* Some other related changes.
* _ResourceManager: allow resources to be named anything as long as they
inherit from the base resource class; gave resources proper names.
* Renamed BaseCommand to Command and BaseTask to Task; applied renames
throughout earwigbot.commands and earwigbot.tasks.
* Data: refactored argument and command parsing to be completely internal.
Added docstrings to attributes. Applied changes to Frontend.
* IRCConnection: improved such that we accurately detect disconnects with
server pings; timeout support. Applied changes to Bot.
* Updated documentation and other minor fixes.