Always return refreshed category
* org-icalendar.el (org-print-icalendar-entries): Do not manually
refresh categories.
* org-clock.el (org-clock-insert-selection-line): Do not manually
refresh categories.
* org.el (org-get-category): Refresh categories if no category found.
(org-entry-properties): Do not manually refresh categories.
(org-prepare-agenda-buffers): Do not manually refresh categories.
It seems a very bad thing to call manually for a category refresh. It
seems better to try to refresh if we do not have a category.
Signed-off-by: Julien Danjou <julien@danjou.info>