Change from mysql-like metadata queries to sqlite-style.

[jasonwyatt]

Currently DebugPort uses MySQL-ish queries to get metadata about the current database or its tables:

• SHOW CREATE TABLE
• SHOW DATABASES
• SHOW TABLES
• EXIT;

I think it would be better to move to queries/commands that are more similar to how SQLite itself works..

• .schema [table name]
• .databases (not really part of SQLite's lexicon, but would apply for android dbs)
• .quit
• etc.