Buffers to updated or removed projects should get flushed

[ngwese]

When selecting a script in the file tree the file is read into an editor buffer. If the project is updated or deleted then installed the older buffer contents will be retained leading to potential confusion.

More optimal behavior would be to refetch all non-dirty file contents on selection.

[ryanlaws]

Do you have a general strategy in mind for managing dirty files?

On a related note, which I think I mentioned elsewhere (I should probably make an issue), I would like to see the "install" button change to "installed" or "remove" when a package is already installed.

Edit: based on #162 it sounds like these are already in there... I'm confused!