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

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