Introduce utcp_connect_ex().

Introduce utcp_connect_ex().

This takes an extra argument "flags", which can be used to change the type
of connection to create. Possible flags are UTCP_INORDER, UTCP_RELIABLE and
UTCP_FRAMED, which can be bitwise-or'd together, or UTCP_TCP or UTCP_UDP as
shortcuts for what is assumed will be common combinations of those flags.