This begins a big refactor of moving more code out of the Gui struct into contexts, controllers, and helpers. We also move some code into structs in the
gui package purely for the sake of better encapsulation
The "open" command is supposed to behave in the same way as double-clicking a
file in the Finder/Explorer. The concept of jumping to a specific line in the
file doesn't make sense for this; use "edit" instead.
