Bug fixes for ox-koma-letter.el
* ox-koma-letter.el: updated documentation and improved defcustoms.
(org-koma-letter-special-tags-after-letter)
(org-koma-letter-special-tags-after-closing): now symbol.
(org-koma-letter--get-custom): falls back to value
(org-koma-letter--prepare-special-contents-as-macro): let
newlines be handled outside of the function
(org-koma-letter--remove-offending-new-lines): function to add
new lines.
(org-koma-letter-headline): updated to work with symbols and
made more robust.
(org-koma-letter-export-to-latex): reset
=`org-koma-letter-special-contents'= to nil
Signed-off-by: Alan Schmitt <alan.schmitt@polytechnique.org>