Support multiple ORDER BY terms in SQLConstructor
No reverse option for SQLConstructor

This is not SQL standard.
Add "search --sort-by-cwd-distance" option
Add test_search_command_by_cwd_distance
Make sql_pathdist_func doctest clearer

Also this may speed up it a little bit.
Merge branch 'sort-by-cwd-distance'
Remove unused method: DataBase._join_environ
Refactor _add_environ_search_1
Comment on _add_environ_search_1
Add missing @classmethod to _compile_sql_search_command_record
Add iterutils.include_before/after
Implement "search  --*context" options
Allow multiple --sort-by options
Implement --context-type
Merge branch 'context-search'
Add short flag -y for --sort-by-cwd-distance
Sort by count by default.
Bump to 0.1.3.dev2