Compare keys improvements
Fixes #132 (closed) #140 (closed) #174.
- Metadata and unchanged info is now hidden by default, two buttons in the top-right corner enable to show them
- A button to get back to the parent key has now been added when browsing through the key tree
- The layout of the page has been restyled to be more compact
- The sidebar dropdowns have been changed to give priority to the valid modes when showing the first 50 ones