Item name and mod abbreviation input validation

[elifoster]

The item names and mod abbreviations must go through input validation to ensure we don't have errors by putting weird characters in them. Both of these must match $wgLegalTitleChars (see also #56) to be valid for page titles.

After this is implemented, someone will need to run a script to check all tile names and mod abbreviations that they are valid. For invalid chars, someone will need to manually update the database directly (since invalid characters prevents you from saving any changes after the invalid characters are added).