Interpolate SF on reference well

[jonnymaserati]

Added clearance.ISCWSA method get_sf_mins for calculating the minimum Separation Factor (SF) between reference well survey stations where a SF minima is determined versus the reference well.

Released as a major update as the SF attribute data format has changed, so this version may not work with code developed for v0.4.x.

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This discussion was created from the release Interpolate SF on reference well.