Feature: Identify object "families" using segmentation data

[freemansw1]

This is a long-promised feature to identify object families/systems by identifying where segmented objects touch.

I think this could probably use some more documentation beyond the docstring, but I wanted to get the feature in PR form first.

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[github-actions]

Linting results by Pylint:

Your code has been rated at 8.72/10 (previous run: 8.72/10, +0.00)
_{The linting score is an indicator that reflects how well your code version follows Pylint’s coding standards and quality metrics with respect to the RC_v1.5.x branch.
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[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (2e4c9d0) 56.91% compared to head (95063e7) 57.18%.

Files	Patch %	Lines
tobac/utils/general.py	92.30%	2 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##           RC_v1.5.x     #398      +/-   ##
=============================================
+ Coverage      56.91%   57.18%   +0.26%     
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  Files             20       20              
  Lines           3440     3466      +26     
=============================================
+ Hits            1958     1982      +24     
- Misses          1482     1484       +2     

Flag	Coverage Δ
unittests	57.18% <92.30%> (+0.26%)	⬆️

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[w-k-jones]

Thanks for adding this feature! I've added some suggestions in the review. Further thoughts:

1. this acts similar to a merge method, does it fit better in the merge/split module?
2. Can we add a complimentary feature to merge tracks where the segmented features are merged together?
3. Could we add an option to erode labels or require a minimum number of adjacent pixels to merge features? This may break the current approach using regionprops

[w-k-jones]

Suggested change

	out_families[time_index] = segmented_arr
	out_families[time_index] = family_labeled_data

Currently output grid is all ones for segmented area.

[w-k-jones]

We should offset the value of these labels by the previous highest feature family so that the families are unique over time

[w-k-jones]

Naming suggestion: "cluster" for a collection of features at one time step