WIP - Refactor methods to be directly associated with class. Yet to do same to fetherApp.emit for setupAppListeners

* Update Readme with Usage of taskbar mode on macOS and Linux

* Remvoe custom context menu since was not working and we will use ALT version instead

* Rename processMoved to saveWindowPosition

* Fix by savingWindowPosition when user minimises Fether window so it restores to same position

* Change tooltip message to 'Click to toggle Fether window' since it is important on Linux as use must click the tooltip to open/close the Fether window

* Only disable taskbar mode on Windows

* Save Fether window position on Linux using debounce with 'move' event, and 'close' event

* Save Fether window position on macOS and Windows also using 'close' event instead of just 'moved' event

* Refactor `create` method to prevent duplication

* Refactor to organise event listeners into `setupWindowListeners` and `setupRequestListeners`