This is the only way to limit the execution time of a possibly long-running python statement.
Use this on String.re, due to the possibility of pathologically long re matching in python.
This allows us to remove the 'trusted-only' restriction on string.re.
In the future, this should probably be used in other places that take user-supplied regexps,
such as 'misc last --regexp', for example, as well as other potentially long-running tasks
that can block the bot.
Conflicts:
plugins/String/plugin.py
src/commands.py