(QCfeature, QCdatagram): Removed variables.

(QCfeature, QCdatagram): Removed variables.
(QCtype, Qdatagram): New variables.
(network_process_featurep): Removed function.
(Fmake_network_process): Removed :feature check.
Use :type 'datagram instead of :datagram t to create a datagram
socket.  This allows us to add other connection types (e.g. raw
sockets) later in a consistent manner.
(init_process) [subprocess]: Provide list of supported subfeatures
for feature make-network-process.
(syms_of_process) [subprocess]: Remove QCfeature and QCdatagram.
Intern and staticpro QCtype and Qdatagram.
(syms_of_process) [!subprocess]: Intern and staticpro QCtype.