Fix a memory allocation bug for simplified variant

The simplified variant option (conv parameter in
cangjie_get_characters()) generates memory error.

The bug is now fixed.
Simplified variant result grouping and minor fix

1. The result of simplified variant query will be grouped by
   the simplified variant character. This will fix duplication
   where the character is a simplified variant of itself and
   another character (e.g. 后)

2. Fixed a minor bug in shortcode query. It was mistakenly using
   SIMP_QUERY. Is changed back to BASE_QUERY