(#859) PvP Blacklist functionality is being re-tooled.

While initially not included in #859, discussion brought with it the need for these changes, as well.

• The blacklist level will be toggleable from the start. A player can choose to only blacklist messages, or messages and attacks.
• If the option to block messages and attacks is selected, it will an entry for both users so they are both blacklisting each other. The only way to remove this is for both players to remove their respective entries. This is a heavy handed approach that is unfortunately needed.
• If players have each other blacklisted with the no attack level, neither will be able to see each other in-game on the map/play page. They will essentially stop existing for each other as both users 'block' the other.
• If a user removes the no-attack level of blacklist, it will not reflect for the other person. This is intended. Some more thought may be required for this, but this is the direction I am going for now.