Survey

This releases adds a few small improvements to survey:

* Fixed a bug that prevented `survey.Required` from allowing any response from a `survey.Confirm` prompt.
* the cursor in `survey.Select` and `survey.MultiSelect` can now be moved with j/k to emulate vim keybindings

This release adds the ability for the user to specify a transformer for a particular field in order to change the user's input into any other arbitrary value.

Added support for casting answer to nested types
* added tests for copying nested structures with casts

* added tests for copying nested structures with casts

* cleaned up test

* added tests for editor prompt

* fixed issue preventing nested casts

* fixed typo in comment