org-metashiftleft/right should honor org-support-shift-select

[Carlos Pita]

Hi all,

on macOS option-shift-left / right extend the selection by one word.
Emacs by default binds meta-shift-left / right in a way that is
compatible with the system shortcuts. But org-mode interferes with
these bindings even when org-support-shift-select is t. OTOH, an
effort has been done to support shift selection in
org-shiftcontrolleft / right. The problem is that macOS uses option
instead of control to achieve selection by word.

Best regards,
Carlos