Implement czchen-10029
Setup trie for new word, not previous words
Add load_word
Check length before doing trie search
Add comment for new algorithm
Use is_one_step to find any predecessor in ladder
Fix wrong increase
Fix debug message
Fix off-by-one
Remove unused define
Merge branch 'czchen/10029'

* czchen/10029:
  Remove unused define
  Fix off-by-one
  Fix debug message
  Fix wrong increase
  Use is_one_step to find any predecessor in ladder
  Add comment for new algorithm
  Check length before doing trie search
  Add load_word
  Setup trie for new word, not previous words
  Implement czchen-10029