[FIX] website: editor: preserve label and color for link buttons targeting a page

When selecting a page target rather than a static
URL the style and label information were ignored/lost.
[FIX] web: push render value deferred only if the field is in a form view
[FIX] mail_thread: allow to pass mail_track_log_only in the context to remove the subtype of the notification. By this way, no mails will be sent because partners_to_notify will be empty.
[FIX] web: even if there is no view, the field has to be rendered

This is related to ÿ07f3f4d9206d4c1a3e484eb89f09d2258977a
[FIX] product: correct name_get for products with resellers.

Error introduced during forward-port commit 14f3085