Changed the loader to pull *.rkt files from zip containers.

Modified the BasicFrame so it doesn't automatically open the Rocket configuration dialog when opening a new rocket.
Unified the behavior for replacing (automatically closing) the base frame when opening a file, loading an example, or picking from the Most-recently-used list.

git-svn-id: https://openrocket.svn.sourceforge.net/svnroot/openrocket/trunk@948 180e2498-e6e9-4542-8430-84ac67f01cd8