Improve the pingif's versatility.
Improve the pingif's versatility.

This merges !pingpref into !pingif, and allows for more user options, as
to how to get pinged. Default behaviour pings people once when their
desired player count is reached, and can be changed with !pingif as
well.

Cr0wb4r/lykos,Diitto/lykos,Agent-Isai/lykos,billion57/lykos