Updated DB Builder to parse 3 or more code

Previously, the sqlite3 database builder (dbbuilder.c) can only
parse the Cangjie3 and Cangjie5 fields with maximum 2 codes. It
cannot properly parse the changes of data/table.txt in the last
commit (13e456d).

To tackle, the function insert_line() has been changed. It can
read any number of comma-separated values in these 2 fields now.

This commit fixes these 2 issues:
https://github.com/Cangjians/libcangjie2/pull/2
https://github.com/Cangjians/libcangjie2/issues/3