Schemas about fsql

[sbuberl]

I'm going to call this done. Still want to add SET CATALOG and SET SCHEMA as SQL standard alt for MySQL's USE, but that can be done at any time. Plus those can easily be done with the API.

Added CREATE and DROP SCHEMA. Added SQL functions current_catalog() and current_schema() to get the name of current selected db and schema respectively.

Table and sequence names in queries can now have three parts: db name, schema name, and the name. db name and schema name are optional there is a selected db/schema.