Imported from archive.

* menu (menu:activate_avatar): Add a default of the first avatar in
the list.
(menu:choose_name): Change the generate more names choice from m to
g and make it the default.
(menu:delete_avatar): Make abort the default choice and correct a
misleading copy/paste error in the prompt.

* menu (menu:delete_account), mudpy.py (User.delete): New menu and
supporting method to allow deletion of an existing account.

* mudpy.py (Element.get, Element.getboolean, Element.getdict)
(Element.getfloat, Element.getint, Element.getlist): Reworked
default parameter handling to fall back to the None type and then
replace it with the appropriate type of empty variable if not
overridden, solving obscure bugs arising from mutable sequence
reuse.
(get_choice_action, get_choice_branch, generic_menu_handler):
Consolidated default choice fallback into generic_menu_handler.

* testdata: Removed pending something better.