Various appdata fixes and improvements
Assamese translation updated
Updated Spanish translation
Fix the name of the appdata file

Unfortunately this is required to match the desktop file.
Updated Dutch translation by Erwin Poeze
Tajik translation updated
Updated Hebrew translation
Updated Lithuanian translation
Updated Czech translation
Updated Czech translation
Update number base documentation.

Add documentation for conversion using "in" operator.
Remove outdated settings entries.
Edited somehow to add some markups (Baptiste)

https://bugzilla.gnome.org/show_bug.cgi?id=720677