Changed behavior of "Escape" - Clear filters. CTRL+W is used to close repository.

As described in issue #2189.

With this change, pressing escape does the following:
* **If** text filter is enabled, clear filter
* **Else if** branch filter is enabled (by text or by "Show current branch only"), clear branch filter and show all branches

So to clear both text filter and branch filter, the user would need to press escape twice.

To close the repository, which was previously done with Escape, is now done via a CTRL+W hotkey (configurable).