cangjie: Use the GLOB operator

We are currently using the LIKE operator to run the SQL queries which
contain a wildcard.

That means we have to transform the wildcard inputted by the user ('*')
into the wildcard accepted by the LIKE operator: '%'.

But SQLite supports the GLOB operator, which uses shell-like globs. That
means its wildcard character is the '*', the same as the one inputted by
the user.

Sounds like a win.
cangjie: Sanity-check the input code

All Cangjie codes are at most 5 characters long.

Let's avoid running into some weird corner-cases where we return funny
stuff by validating our input a minimum.
cangjie: Sanity-check the input code

The shortcode stuff is used for special characters like punctuation or
symbols, e.g , ? . # @

It is meant to always only take a one character long input code.

Let's avoid some bizarre issues by validating our input a minimum.
Merge pull request #29 from Cangjians/input-code-mangling

Input code handling