Removed testApi module, added comments, refactored

The testApi module's job is being handled by the API directly. Later
I may implement a mechanism that makes it more straight forward, but
for now it works.

Comments have been added to each function, type, package etc.
Not too much but just enough to briefly explain what everything does.
Also added a header at the top of every page with a copyright and
license statement.

Refactored out some common code especially in lib/auth. Common
database table schemas have been refactored to a separate package
lib/dbschema. This will allow for centralized control. Specific
schemas will need to be created by the functions themselves, but
for any 'SELECT *' statements, the schemas here should be good for
SQLx.