Find any useful fixes from the PRES BASIC Editor

[tom-seddon]

There's the odd interesting-looking change, that I've just blindly applied to the buildable copy without really thinking about it. Some examples.

• basic_editor/pres/bedit/pres_bedit.reset_keys_settings.s65

  Line 21 in d6a6a06

  .if acornsoft_version

• basic_editor/pres/bedit/pres_bedit.s65

  Line 321 in d6a6a06

  .if acornsoft_version

• basic_editor/pres/bedit/pres_bedit.s65

  Line 799 in d6a6a06

  .if acornsoft_version

• basic_editor/pres/bedit/pres_bedit.s65

  Line 1487 in d6a6a06

  .if acornsoft_version

Go through the full list and pick out anything that's worth keeping.