v0.9.0

• Add Panui_result.of_msg.
• Add better DOM management primitives to Panui_scalar.
• Add string_textarea and string_option_textarea to Panui_scalar.
• Add ?step argument to emit and set functions in
  Panograph_event_table and Panograph_signal_table.
• Rewrite Panograph_signal_table to avoid Obj.magic.
• Fix delay issue for read-only selection.
• Deprecate the rest of Panograph_basic_editors.