Engine-Tests: added test-case for "-only JSON de-serialization bug
Frontend-GNOME: pixel perfect topic and user list alignment
Frontend-GNOME: moved user count from user list to window title

BUG: the initial width of the user list is now incorrect and has to be fixed!
Frontend-GNOME: use 1/6 width as default size for user list and adapt with window resize (closes: #917)

This fixes the bug mentioned in 32885265bd04e667b0c94caab64ee1d3b6056556