Default BSI base value to min, max, or 0 depending on the min/max range

[travisturner]

Overview

The BSI base value determined by FieldOptions.Base was defaulting to 0 (except in cases of migration from v1 of BSI). This PR changes the logic to set the base to either min, max, or 0 depending on the range of min/max.

Fixes #2013

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[travisturner]

I just realized we may need to apply this same logic to the migration code in Field.loadMeta() as well.

[travisturner]

I pushed another commit to apply that same logic to the migration from v1 code.