Baselined subject weight is not computed and logged correctly

[glopesdev]

The current subject weight is not baselined since the baseline trigger is never activated and only the FilteredWeight field is accessed during subject weight measurements. Also the calculation of the baseline trigger event is using the number of detected SLEAP pose bounding boxes, instead of the number of stable subjects in the arena center, which is error prone since multiple bounding boxes with the same ID can be reported by the model. Points for consideration:

• Use StableSubjectsInArena for triggering the baseline. This will cap at the absolute maximum of observed animals and also avoid spurious triggers since it has a temporal smoothing component.
• Route BaselineTrigger subject to BaselineWeight subject (or replace the former with the latter). The BaselineWeight command was introduced as part of the WeightScale module to simplify logging and interfacing when scaling up to multiple scales in the future.
• Use BaselinedWeight for computing subject weights.
• Consider whether we want to record the BaselinedWeight. ~One interesting option here would be to record a single three-column Harp bin file with raw / filtered / baselined weights instead of two or three separate files [NOTE: actually it is not just three-columns because of measurement confidence].~

[glopesdev]

Use StableSubjectsInArena for triggering the baseline. This will cap at the absolute maximum of observed animals and also avoid spurious triggers since it has a temporal smoothing component.

Actually, on further inspection the current baseline trigger logic is using SubjectsInArena which already ensures a capped count. The baseline trigger period needs to be adjusted and tested.