Make some minor performance & UI changes to AutoConfigMaker.

-Provide more information in error dialogs on failed configure attemtps.
-Make some minor performance tweaks.

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The biggest change here is the extra info relayed to the error dialog in failure cases. I wanted the dialog to make a distinction between finding duplicate interpreters and actual errors, and to provide the user with a little more information than I had it say before. I apologize if the "found duplicate/error" trackers are a bit messy, but I couldn't think of anywhere else to put them that would accomplish the same purpose without being too complicated.