Previously, ids could only be created with an ip address. Now they can
be made with a hostname, which will be looked up by UDPC.
Also fix client still requesting connections even if
accept-new-connections flag is false.
The "data" member variable in UDPC_PacketInfo is now handled as a
pointer to dynamic data, instead of an array with a fixed size. Every
time a UDPC_PacketInfo is received from the context,
UDPC_free_PacketInfo() must be called on it to avoid a memory leak.
