Persist stage position from end of session, not start

[galenlynch]

If the operator moves the lick spout position during a session, then the new location will not be stored. Instead, the position of the lick spout at the beginning of the session is stored. As it's difficult to know the best spout position before running any behavior, it's natural to have adjustments 'online' in the first few sessions. Currently, you must keep track of these adjustments by writing them down and remembering to 'replay' them before the start of the next session. Unfortunately for us, we had ~1 week of forgetting to set the position at the beginning of the session.

From discussions with @bruno-f-cruz this may require disabling the rapid retract feature to be safely implemented.

[bruno-f-cruz]

I can see three options:

1. We remove the retraction feature (currently no one is using/planning on using it) which makes this whole thing trivial.
2. we have a conditional that only allows people to save the new position during the session if not using the operation control. This is super hacky and hard to maintain; I will probably not go with it
3. We have a "hammer" approach where the task is halted manually and then users are allow to move the stage. I think this will be super complicated for operators and likely to affect the animal's behavior.

I am overal leaning towards 1. as it would mainly be a subtractive approach.

[bruno-f-cruz]

Going with removing the feature of retraction.

An implementation has been attempted in #577