Rework `orgstruct++-mode' so that you can turn if off safely.
* org.el (org-auto-fill-fallback-function)
(org-indent-line-fallback-function)
(org-fill-paragraph-fallback-function)
(org-auto-fill-fallback-function)
(org-indent-line-fallback-function)
(org-fill-paragraph-fallback-function): Remove.
(org-fb-vars): New buffer-local variable.
(orgstruct++-mode): Use the fallback variable `org-fb-vars' to
store, use and restore variables if needed.
(org-fill-paragraph): Ignore `orgstruct++-mode' filling
variables when needed.
(org-auto-fill-function, org-indent-line-function): Ditto.
* org-macs.el (orgstruct++-ignore-org-filling): New macro.