exp/locale/collate: changed trie in first step towards support for multiple locales.

exp/locale/collate: changed trie in first step towards support for multiple locales.
- Allow handles into the trie for different locales.  Multiple tables share the same
  try to allow for reuse of blocks.
- Significantly improved memory footprint and reduced allocations of trieNodes.
  This speeds up generation by about 30% and allows keeping trieNodes around
  for multiple locales during generation.
- Renamed print method to fprint.

R=r
CC=golang-dev
https://golang.org/cl/6408052