- make db path portable.
  - reuse libpyzy main db and user db logic.
  - auto create user db (tables, indices) if it doesn't exist.
- added create-deb.sh, it can create deb file for debian.

format code using myastyle.
removed space after function name.
put pointer on variable name side.

- CommitCandidate allow save phrase and user_freq in user db.
- bugfix: GetCandidates SQL query ORDER BY field fixed.
- bugfix: fix a memleak in on_handle_get_candidates()
- minor bugfix: fix variable name in meson.build

now xi'an etc types okay.

this method allow user to delete candidate so they won't appear in
future queries.

use release build for file in that path.
add ninja install target.

make code compile in release mode. no unused variable.

otherwise the group by command only applies to the 2nd SQL.

enabled some fuzzy pinyin support.

simplified the SQL query, remove the top level wrapper. it's unnecessary.

get_candidates() implemented naively.

no jian pin support, no auto correction, no ambiguity pinyin support, but here
is a good foundation to work on.

working on get_candidates().