[FEATURE] - Double click to open source properties

[nacalai]

Since double-clicking a source open its properties, one would expect the same behaviour in QAU. My brain auto-piloted and tried double-clicking with nothing happening. My brain got sad.

Nothing big..but would be neat!

[FiniteSingularity]

This is related to #62. The double click handler is a bit tricky due to the custom list views that were created. I'm working on getting a reliable double click to work, and once I do, will consider adding this functionality as well.