Fix/jump to

The :editor.jump-to command did not push the initial position to the stack. This made the stack pretty useless for stringing together commands. If for some reason this isn't good to do by default I can add an optional param to the command to enable or disable it. One use case enabled by this:

```clojure
     :editor.scss {"ctrl-c ctrl-t" [(:editor.jump-to "/home/josh/repos/phobos/lightshow/css/theme.css")
                                    (:eval-editor)
                                    (:editor.unjump)]}
```

In this case, there is an existing SCSS plugin, but it requires a lot of setup outside of LT with outdated documentation on the process. until I have time to look into helping patch that up this fills the gap (and can similarly be used by others for more complex LT automation).

I also changed `move-cursor` to accept an arity of 1 (jumping to the first line if no line is specified). This was the existing behavior, but now it doesn't error out.

Cheers