Add preferences menu with keybinding entries.
Add option to view results in new buffer.

This adds a settings file with a single setting, "results_in_dialog," which is
true by default. When this setting is set to false, the validation results
will be displayed in a new file instead of a dialog.
Add commands to command palette.
Break an excessively long line.
Add an explanatory comment to the settings file.
Change a variable name to clarify code.
Merge pull request #3 from blinskey/master

Add option to view results in new buffer and command palette support