- Adds more keys under `<localleader> a`
- Reconfigures org-download to use org-attach system
- Make org-id-track-globally = t a global default now (not just for
org-brain)
- Renamed +org-init-centralized-attachments-h to +org-init-attachments-h
- org-attach-store-link-p = t (stores a link to an attachment when it is
attached)
- org-attach-use-inheritance = t (inherit attachment properties from
parent nodes)
