Add register_type() for parsing user types, add test and example

[oir]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 12001502625

Details

• 28 of 32 (87.5%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.1%) to 94.713%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
startle/_type_utils.py	19	23	82.61%

Totals
Change from base Build 11999150001:	-0.1%
Covered Lines:	627
Relevant Lines:	662

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💛 - Coveralls