Reveal cursor on panel expand

@peterflynn Simple fix for issue #3003, and (nearly) identical to closed and outdated pull request #3931.
Something like:
```
Determines if the cursor is currently visible and if not, scrolls the editor view port to make it visible. The distance between the cursor and the bottom is maintained, unless the cursor scrolls up higher than the editor center in which case line with the cursor will be centered.
```