#93 Add option to remove unused imports

[Chris Arrowood]

An easy one:
Add an option to remove unused import statements. If
enabled in the config, it would cycle thru each import
statement; If the class that is imported is not found
in the code, remove that import statement.

For instance:
import java.awt.BorderLayout;

If there are no lines that contain thew
text "BorderLayout" then remove the import.

... Yes, I AM that lazy! ;-)

Keep up the good work. I use this Pretty Printer all
the time!