Plugin Message (0xFA) Handling

Added a module which handles the sending/receiving of Plugin Message (0xFA) packets.

Distributes the packets as appropriate, and handles client registration/deregistration from non-built-in channels.
MCPP|Brand Handling

Added a module to handle the built-in plugin message channel "MC|Brand", which communicates the "brand" of servers/clients back-and-forth.

This information is sent to clients, received from them, and stored in a way that mods may consume.

Also added a module so operators can view the "brand" of all connected clients.
Module Information

Server operators can now query information about the module loader and loaded modules through the /info system.
Clients Information Cosmetic Change

/info clients no longer lowercases usernames before output.