First attempt at implementing configurable monitor subscriptions using p2p communications instead of shared bus.
More work on monitor subscriptions: added /subscribe message handler with granular control over items of interest (device, inputs, outputs, links, connections). Changed device sync ping to include name, also use for response to /who message. Detailed device metadata available through subscription.
Switched monitors to subscription model.
Added subscription-autorenew functionality to monitor.
Remove monitor request functions.
Store mesh admin port of remote devices in router/receiver datastructure, use for p2p admin responses.
Python: switch to monitor subscription model.
Properly handle changing flags for existing subscriptions.
Send /connectTo message p2p since link src is known. Test programs using monitors need to wait for link to be established before connecting.
Return correct number of file descriptors.
Merge branch 'admin2' into admin2-simplify
Remove admin functions related to monitor queries.
Fixed bugs in signal removal from db.
Monitor: remove auto-renewing subscription when device logs out.
Merge branch 'admin2' into admin2-simplify

Conflicts:
	src/monitor.c
Expression parser: add TOK_ASSIGNMENT, enable vector indexing on output variable (y). This will allow null-padding of mapped signals when mapped to partial vectors, as well as assignment to possible additional variables in the future.
Expression parser: build typestring for evaluated expressions will nulls for missing vector elements.
Handle null-padded signal updates at receiving device. Switched to using generic OSC typestring handler since details of null-padding cannot be known auntil runtime.
Use null-padding for default linear/calibration expressions in cases when dest_len > src_len.
Fixed bug initializing has_complete_value flags for new signals.