Configuration Improvement

[curlpipe]

This is an update I've wanted to do for a while - just an improvement to the configuration system which currently has a few limitations

• Tweaks to make configuration files a little cleaner and clearer
  • Add back the key bindings to change tabs
  • The status line should clear itself automatically if defined in two separate config files
    (built-in vs user-defined)
• Different plug-ins should be able to share the same key binding
  (at the moment, they overwrite each other)
• Expanded configuration areas
  • Modify the tab width, undo committing period and cursor wrapping behaviour
  • Control the amount of padding surrounding line numbers
  • Tab line can be optionally removed or formatted differently
• Better error & warning system
  • Warning when no default configuration file detected
  • Warning when trying to import a plug in that doesn't exist
• Better documentation and support
  • Update readme key bindings
  • Update documentation with key bindings
  • Document new editor API function calls