Changed
- Calling `all_variables(simplify=False, include_internal=False)` now
omits `_internal`.
- The HTML now uses `required` and `aria-required="true"` to indicate
required fields.
Fixed
- `interview_url()` can now receive `session` without also receiving
`i` and `i` will be set to the current filename without overwriting
`session`.
- Calling `create_session()` and other functions for manipulating
other sessions could disrupt `_internal` variables in some
circumstances.
- `url_ask()` can now begin with an action.
- Error in session deletion that caused sessions not to be deleted in
some circumstances.