Rename some variables
Rename some variables

The word "cursor" is quite ambiguous, so trying to make it clearer.

Also clean up Option<Vec>, just test that it's empty.

modelorganism/xi-editor,google/xi-editor,google/xi-editor,fuchsia-mirror/third_party-xi-editor,modelorganism/xi-editor,modelorganism/xi-editor,fuchsia-mirror/third_party-xi-editor,google/xi-editor,fuchsia-mirror/third_party-xi-editor,google/xi-editor,fuchsia-mirror/third_party-xi-editor