AP_RangeFinder: support multiple MAVLink rangefinders via RNGFNDn_ADDR

[tridge]

Summary

Allow multiple MAVLink rangefinders by using RNGFNDn_ADDR to select which DISTANCE_SENSOR message id each backend accepts.

Classification & Testing (check all that apply and add your own)

• Checked by a human programmer
• Non-functional change
• No-binary change
• Infrastructure change (e.g. unit tests, helper scripts)
• Automated test(s) verify changes (e.g. unit test, autotest)
• Tested manually, description below (e.g. SITL)
• Tested on hardware
• Logs attached
• Logs available on request

The existing Copter RangeFinder autotest is extended to configure two MAVLink
backends with RNGFND1_ADDR=1 and RNGFND2_ADDR=2, feed DISTANCE_SENSOR
messages with each id in turn, and check that the reported distance shows up on
the matching backend only.

Description

Previously the MAVLink rangefinder backend filtered incoming DISTANCE_SENSOR
messages on orientation only, so two MAVLink rangefinders with the same
orientation could not be distinguished and both backends consumed every message.

This adds an id filter based on the existing RNGFNDn_ADDR parameter:

• RNGFNDn_ADDR of 0 keeps the old behaviour and accepts any DISTANCE_SENSOR id
• a non-zero RNGFNDn_ADDR only accepts messages whose id field matches

The ADDR parameter documentation is updated to describe the MAVLink use.

[peterbarker]

Code changes LGTM.

Approved after the test is fixed.

I'd actually prefer a completely new test for this functionality rather than shoving it into the existing test - but I'm not going to insist.

[peterbarker]

Suggested change

	self.context_stop_collecting("DISTANCE_SENSOR")
	self.set_parameters({
	"RNGFND1_ADDR": 0,
	"RNGFND2_TYPE": 0,
	})
	self.context_pop()

[peterbarker]

Suggested change

	self.set_parameter("RNGFND1_TYPE", 10)
	self.set_parameters({
	"RNGFND1_TYPE": 10,
	"RNGFND1_ADDR": 1,
	"RNGFND2_TYPE": 10,
	"RNGFND2_ADDR": 2,
	})
	# we are interacting with the autopilot, reduce chance of
	# hitting timeouts on supplied data:
	self.context_set_speedup(1)
	self.set_parameter("RNGFND1_TYPE", 10)
	self.context_push()
	self.set_parameters({
	"RNGFND1_ADDR": 1,
	"RNGFND2_TYPE": 10,
	"RNGFND2_ADDR": 2,
	})

[peterbarker]

Is this needed?!

[peterbarker]

Suggested change

	# we are interacting with the autopilot, reduce chance of
	# hitting timeouts on supplied data:
	self.context_set_speedup(1)

[peterbarker]

This was leaking into subsequent tests, thus the extra push/pop