travis.yml: Add IRC notifications.
Add explicit/helpful error message about how to solve the multiprocessing 'Permission denied' issue.
Add class attribute callbacks.Commands.pre_command_callbacks.
utils.str.format: Replace %u with '' instead of '<>' if URL is empty.
Revert "Web: Disable @title and @doctype for non-HTML documents." (incompatible with Python 2)

This reverts commit 34b0e5faadf7c042bd911cdc392e673e6889fa0e.
Aka: Fix import of locked alias.