Re: delete-selection-mode as default

[Juri Linkov]

> But before that I'd appreciate if we could improve its implementation so
> it doesn't rely on pre-command-hook.

Reimplementing delete-selection-mode to be more like shift-select-mode
will also require to get rid of putting 'delete-selection props on
command symbols, and like shift-translated commands have a `^' character
in the `interactive' spec, delete-selection-mode might require a separate
character.  Hopefully, these types of commands are mutual exclusive,
so their disjoint sets won't cause conflicting interactive specs.