File selection dialog update, part 1

This adds a replacement for the SelectFilesDialog class.  It has
been updated to use Explorer-style dialogs, which are a bit nicer
than the old-style dialogs.  Hopefully this will eliminate some of the
brain damage, like the disappearing Accept button.

This change only updates MDC.  A second change will update the main
app and remove the old code.

Also, updated the MDC version to 3.0.0, and changed the web site
linked in the Help menu from faddensoft.com to a2ciderpress.com.