Log Message:
Update to 2.17
all changes for pthai.el
- remove some unnecessary split methods and related customize settings
- simplify and optimize 'pthai-split-all, reducing redundant word splitting
- rename pthai-spell-correct-p -> pthai-spell-p, fix check for single char words
- clarify few function descriptions
- replace 'remove with 'delete in a few places
- remove pthai-completing-read-mode and ido prompt customize option
- replace pthai-completing-read with pthai-completing-read-full/dynamic,
  allows for thai word completion to be add to some functions