Added copy to clipboard functionality and a few hotkeys.

[strange-v]

I was surprised that it isn't possible to copy query results into the clipboard, so I added such functionality + hotkeys.

Tabs middle mouse click - close tab under the cursor QueryControl F5 - run the current query QueryResultsControl Ctrl+A - select all Ctrl+C - copy to clipboard

[mr-manuel]

For those who are searching a compiled version with this feature, you can download it from my fork.