bos/critbit — pull request #57 by kgeorgiy (2013-05-29 20:17:30+00:00)
Title: Implemented isSubmap, isSubmapBy, isProperSubMap, isProperSubmapBy

Based on pull request #55 by @isturdy.

Implementations of `isSubmapBy` and `isProperSubmapBy` made mutually recursive. This implementation is 25% faster than in `Data.Map`.