Prevent DoS of dice expressions

[Cory Dodt]

e.g. [500d100000x50sort]

There are two attacks involved here.
1. It takes a long-ass time to roll all those dice. (It was about 4:00 of CPU time when PenguinOfDoom tried it.)
2. It generates more text than can be sent to the IRC anyway, so the bot gets kicked off by excess flood.

Look for other potential DoS's in the dice parsing as well.

[Cory Dodt (corydodt)]

DoS can be generated by other things too, apparently. Especially long repsonses to ".aliases" can cause the bot to flood itself off.