title: Unmap ctrl+space in Sublime Text 3
body: <p>On OS X, I have ctrl+space mapped systemwide to "Help...Search". However, in Sublime Text 3, the default for ctrl+space is auto-complete. In Sublime Text 2, I was able to edit the default keymap and just delete it, but it seems like you can no longer edit the default keymap anymore. </p>
  
  <p>Is there any way in Sublime Text 3 to "undefine" a keymap so that Sublime will allow the operating system wide shortcut to take effect instead?</p>