Splitting process into proc + lib

The process-based way of doing things does not change in any way.

The new library can work both by using an ETS table globally accessible
to store the configuration (replaces the process), or purely from a
configuration file. It will also open its own UDP socket for each send
rather than using one in a process that gets centralized. This should
come at little cost for local syslog.

It could be interesting to extend the feature to allow pre-existing UDP
ports to be used.