menu: misc settings polishing

Improved layout and labelling

Removed cl_port as it's for very rare corner cases and is a game breaking footgun

Removed cl_movement as nobody should disable it, but sometimes people did by accident or without understanding the effect, also #2549

Added cl_netrepeatinput as this compensation has a cost and hides issues

Modernised speed limit options (should not imply xonotic supports 56k)

Removed 30fps from cl_maxfps options

Added 40fps cl_minfps option, fixes "Custom" being displayed by default

Added an Apply button for the developer setting