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?
Generally, I'm not a great fan of putting conditions in the return statement.

On the other hand, your version has that going for it that it is clear the return is always executed.

With mine, after taking out the original return 0; it is not-so obvious (because of seemingly unrelated conditions) that one of the return statements is always executed (even though the compiler knows it).