Remove telescope_focal_length from camera configuration

[wschoenell]

There is already a configuration parameter focal_length on the telescope instrument.

chimera/src/chimera/interfaces/telescope.py

Lines 47 to 55 in e15ce55

	__config__ = {"device": "/dev/ttyS0",
	"model": "Fake Telescopes Inc.",
	"optics": ["Newtonian", "SCT", "RCT"],
	"mount": "Mount type Inc.",
	"aperture": 100.0, # mm
	"focal_length": 1000.0, # mm
	# unit (ex., 0.5 for a half length focal reducer)
	"focal_reduction": 1.0,
	}

This confuses the user.

[wschoenell]

My idea is to add a key named focal_length on ImageRequest dictionary where the value is set by being the telescope instrument focal_length configuration parameter. And, also, get rid of the focal_reduction configuration parameter. If there is a focal reducer, the user is responsible (and alerted on the documentation) to calculate correct focal length.