Merge pull request #97 from fingolfin/mh/Vector #48

Job	Run time
doctests	1m 2s
test (ubuntu-latest, x64, 1.6)	1m 27s
test (ubuntu-latest, x64, nightly)	2m 16s
test (ubuntu-latest, x86, 1.6)	1m 30s
test (ubuntu-latest, x86, nightly)	4m 7s
test (macOS-latest, x64, 1.6)	4m 30s
test (macOS-latest, x64, nightly)	4m 4s
test (windows-latest, x64, 1.6)	10m 7s
test (windows-latest, x64, nightly)	9m 53s
test (windows-latest, x86, 1.6)	9m 45s
test (windows-latest, x86, nightly)	9m 28s
	58m 9s

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