Log Message:
Update to 2.27
all changes for pthai.el
- reduce some unnecessary splitting and joining of strings
- default to word at point for 'pthai-dictionary-find-word
- make 'pthai-dictionary-find-regexp work same whether interactive or not
- add prefix option for 'pthai-twt-words
- in 'pthai-unknown-words-toggle, display clearer messaging whether words
  toggled on or off, or no words found
- simplify code in a few places