Abstract the structure a bit

[vilim]

Provide abstract classes and (at least) 3 implementations for each:

	Abstract	Missing	Mock	Our LS	Extra
Laser	[x]	[ ]	[x]	[x]	[]
Camera	[x]		[x]	[x]	[] e.g. Andor
Scanning	[x]	[x]	[x]	[x]	[] e.g. LabJack
External comm.	[x]	[x]	[x]	[x]	[]

This would also allow sashimi to be used on e.g. lightfield (supporing Absent implementations) without modifications

[diegoasua]

Do we want a laser missing implementation? Seems like an overkill for now! Also #61 itself is about LabJack and so far we have agreed that we will help anyone trying to implement an Andor or whatever camera here, but there are no plans to write a wrapper for it. However we maintain that other issue for Labjack support. Therefore can we close this after #120 is eventually merged?

[diegoasua]

Also related, start factoring out code to scopecuisine, for example starting with #124