added unit testing

visual studio 2008 native unit testing.
Completed test definitions:
for runNonQueryTest and insertCountryTest.

further disconnecting db from the GUI, changes in tested methods might hav
e broken functionality on untested dependants.

Changes involve removing form element references from public methods: the
password field is now passed in the constructor and its value is saves as
a local, private member.

This means that the WorldDB object must be
instantiated with each use, or at least after a password is collected from
the user. The form constructor cannot divine this value anymore.

This move will be good for multithreading as well.