Make a rtprio-server and rtprio-client option. Leave the server
priority by default to 88 but lower client priority to 83. JACK
does something similar by setting clients to rtprio-server - 5.
Make module-rt use the client priority by default and bump the server
priority explicitly in the config file.
Leave the pulse-server to the default rtprio-client, there is no reason
to lower this any further because it is really just a regular client.
Bump the ffado packetizer thread to rtprio-server + 5 because that is
also what JACK does.
88 is still much higher than the value of 60 that JACK uses in
Fedora but now this is at least configurable.
Remove some includes of private.h
Add some methods to get the mempool of client and context so that we can
remove direct access.
Move some things around.
Use methods to get pw_loop variables.
See #3243
