Issue #283 - Overhaul preferences layout

Fix preferences layout in order to avoid a text above a checkbox. Give
some padding to the screen to increase the readability.
Issue #283 - Fix scrolling bug in Settings screen

Some texts were leaving a trace while scrolling the list. Now the scroll
is smooth. Give some padding to the screen as well, to increase the
readability of the content.
Merge branch 'develop' into feature/appui
Merge branch 'feature/appui' into develop