SimpleString::StrCmp (2)

1. This implementation works
2. StrCmp and StrNCmp should be similarly implemented (whichever way)
3. More complete tests for both
4. @basvodde Not quite what you had in mind?
I guess 'why' is rhetorical, and 'liking' not a good answer :-). I will change it to a for loop when I have a moment to spare, it's not that big a deal.