Merge pull request #1 from UweSchmidt/master

Test mit StringMap und Änderungen in StringMapProperties
use a real dictionary to benchmark StringMap
hlit fixed and some minor improvements

some fixes
added some strict implementations
asses some more strict functions.

(reduced the speed of the strict version by about 5%
Added mapMaybe

This was imported from https://github.com/ulfs/holumbus
commit 16ef0a41e222f91352c515215f6cd0a852e5335a
by Ulf Sauer<ulf.sauer@gmail.com>
minor changes
a simple test with assertNF added