Careful analysis of local variables for sticky agendas
* lisp/org-agenda.el (org-agenda-force-single-file): Variable removed.
(org-prepare-agenda-window): Store pre-agenda window config locally.
(org-timeline): Introduce a scoped version of `org-agenda-show-log'.
(org-agenda-list): Introduce a scoped version of
`org-agenda-show-log'.
(org-agenda-get-progress): Use the scoped version of
`org-agenda-show-log'.
(org-agenda-local-vars): Write the analysis result as a comment - to
be cleaned up in the next iteration.