Find out what maximum for max_peers is

[futile]

When calling Enet::create_host, the max_peers argument sets the maximum peer count. However, the type of this argument is usize, but probably less than usize::MAX peers are supported. Finding out the maximum count most likely needs to be done by looking into the ENet docs + source. It can then be turned into a specific enum like ChannelLimit etc.

[Boscop]

@futile
ENET_PROTOCOL_MAXIMUM_PEER_ID is 0xFFF (4095):
https://docs.rs/enet-sys/0.2.0/enet_sys/constant.ENET_PROTOCOL_MAXIMUM_PEER_ID.html
http://enet.bespin.org/protocol_8h.html
lsalzman/enet#84
See also these threads on increasing the limit:
lsalzman/enet#41
http://lists.cubik.org/pipermail/enet-discuss/2014-August/thread.html#2331