Make sorting channels require conscious effort and show intent

Lots of people accidentally reorder server channels, probably when using touchpads, because all it takes is a quick drag & drop.

Please make changing channel order require clear sign of intent, by e.g.:

• Making it a "press and hold" type thing, where a simple drag isn't enough, but you have to press the mouse button down for 500-1500ms or so before it starts to drag it around.
• Require enabling an "edit mode" 
• Move channel sorting to the server settings