feature request: high level "home" command in moz.el

[retroj]

After using repl.enter, it is frequently the case that the 'repl' object can no longer be accessed, and one is effectively stuck. Breadcrumbs seem a heavy-handed solution to the problem because they modify the environment being inspected. The solution I favor would be to have a "home" command built into the repl protocol itself. Many other repls (slime, sepia, ghci, hugs, ...) follow the convention where a comma at the start of the input denotes a repl command. So my feature request is that moz.el adopt the comma convention, and that mozrepl provide a "home" command which would change the context back to a user-configurable home scope.