feat: Allow __view__ to be a callable.

[DanCardin]

This enables lazy imports or lazy attribute access on a sqlalchemy query object, in order to avoid circular import errors.

[coveralls]

Pull Request Test Coverage Report for Build 9318635502

Details

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 96.668%

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Totals
Change from base Build 9260529761:	0.01%
Covered Lines:	2522
Relevant Lines:	2603

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💛 - Coveralls