With the import feature, we should restructure the CJK collators to move common sequences into separate, internal collators. Example:
und-Hani could also be mul-Hani
Will not delay release for this, so should be done early.
Merging future and UNSCH
share private-kana & private-pinyin rules, nn import nb, use und not root in import source (according to discussion in April)
I did not create shared unihan rules because I plan to move the unihan order (without a rule string) into the root collator.