Api cleanup

[UselessPickles]

While asking for feedback on reddit, I talked myself into imrpoving the clarity of the API. Read about it here: https://www.reddit.com/r/typescript/comments/7ykp3j/typescript_enum_utils_strictly_typed_wrapper/duhrqq5/

[coveralls]

Pull Request Test Coverage Report for Build 89

• 7 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 79:	0.0%
Covered Lines:	96
Relevant Lines:	96

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💛 - Coveralls