- Unified bounary conditions for NFC and NFD and removed some indirections.
   This enforces boundaries at the character level, which is typically what
   the user expects. (NFD allows a boundary between 'a' and '`', for example,
   which may give unexpected results for collation.  The current implementation
   is already stricter than the standard, so nothing much changes.  This change
   just formalizes it.
 - Moved methods of qcflags to runeInfo.
 - Swapped YesC and YesMaybe bits in qcFlags. This is to aid future changes.
 - runeInfo return values use named fields in preperation for struct change.
 - Replaced some left-over uint32s with rune.

R=r
CC=golang-dev
https://golang.org/cl/5607050