Fix the test
Make SplitLabels faster

don't allocate a new string at all, it does not matter is the given
string is not fully qualified.
Add .
Move deprecated function to the bottom of the file
Make CountLabel faster

We don't need an allocation here, it works ok for non-fqdns and fqdns
Add more tests for the labels
Add a PrevLabel function to count back from the right
Fixup PrevLabel and add a test