Add case insensitivity, BanList support, fix bugs

Topic names now case insensitive for reading, changing and deleting, first entry for each topic will contain the correct case as it was defined the first time the topic was added.
Uses a ModDota banlist to ban users from abusing the command. Also added check for if a user is globally banned.
Fixed crash due to IndexError when using the faq command directly without parameters.
Now uses self.rankconvert instead of own dictionary for converting rank symbol to number.
Improved writing in some places.
Attempting to improve tolerance to whitespace, still needs more testing.