Dtype docs, fix scalar serialization

[sneakers-the-rat]

Fix: #52

Also took the oppotunity to add dtype docs, since there have been a bunch of questions about coercion in particular.

TODO:

• general scalar dtype test case and serialization test for all interfaces

[coveralls]

Pull Request Test Coverage Report for Build 16737398577

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This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 10 of 10 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.006%) to 98.309%

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Totals
Change from base Build 14942234863:	0.006%
Covered Lines:	1512
Relevant Lines:	1538

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💛 - Coveralls