Add tests for U::String#dump
Add tests for U::String#inspect

This found an error in handling incomplete characters
Add tests for U::String#ljust and U::String#rjust
Add tests for U::String#to_str
Add tests for U::String#tr_s
Add tests for String#u
Add U::String#new tests
Add U::String#dup tests
Add tainting to U::Buffer#append
Add tests for U::String#eql?
Add U::String#u
Add test for U::String#valid?
Move canonical_ordering outside of decomposition loop

This seems to cut the run time by a third and all tests indicate that
this works fine.
Move canonical_ordering functions
Use decomposition function instead of normalization mode
Fix a potential GC problem

All tests have now been run with GC.stress = true, so it seems that
we’re now Ruby GC safe.  What a joyous occassion!
Add test:normalize rake task
Deal with case result generation separately
Rename to(lower|title|upper) to (down|title|up)case
Validate input before it goes to functions that requires it