pinyin support when parsing pinyin.
otherwise, preedit_str such as rug(uo) will not show two word candidates

- added FuzzyFlag property.
- updated zero-pinyin.el to support zero-pinyin-fuzzy-flag variable.

do not allow omit shengmu.
only allow omit yunmu.

changed some g_message to g_debug to reduce log during normal usage.
especially, do not log user's preedit_str, this could leak sensitive
user data to syslog.

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.

make code compile in release mode. no unused variable.

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

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.