Misc. improvements

[Smibu]

This adds some small improvements that I made while trying to use the library. See commits for details.

[coveralls]

Pull Request Test Coverage Report for Build 243

• 125 of 142 (88.03%) changed or added relevant lines in 6 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.5%) to 93.724%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tests/lev.rs	36	37	97.3%
src/rec.rs	4	7	57.14%
src/lev.rs	32	45	71.11%

Files with Coverage Reduction	New Missed Lines	%
tests/topology.rs	2	90.22%

Totals
Change from base Build 242:	-0.5%
Covered Lines:	1598
Relevant Lines:	1705

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💛 - Coveralls