in BLACS, Zaber stage does not obviously handle when device is not homed

[philipstarkey]

Original report (archived issue) by Chris Billington (Bitbucket: cbillington, GitHub: chrisjbillington).

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Copying and pasting from a comment on PR #85:

The check-if-homed functionality is tricky.

As it stands, if not homed, one gets an error saying that the position is not as expected (remote value check reports the max position if not homed), and one can say ‘keep remote value’ then tell the device to go to position 0 in the GUI to actually home it.

I’ve been playing with ways of getting it to explicitly say ‘hey the device isn’t homed', but have been fighting BLACS' state machine to do so, it’s not really fitting in neatly. I’ll file a separate issue for it and merge this for now.