Fix interface conversion checks.
Update README.md

fix a typing mistake in the example
Merge pull request #18 from fanyeren/master

fix a typing mistake in the example
Merge pull request #17 from statik/interface_conversion

Fix interface conversion checks.
Now with benchmarks.
Merge branch 'master' of github.com:tgruben/go-roaring
Remove duplicated test code.
Merge pull request #19 from statik/remove_duplicated_test

Remove duplicated test code.