org-element: Allow to escape escaping character before a comma
* lisp/org-element.el (org-element-macro-parser): Allow to escape
escaping character before a comma. Also do not trim spaces at
argument boundaries.
* doc/org.texi (Macro replacement): Update documentation about
possible locations and escaping mechanism.
* testing/lisp/test-org-element.el: Add tests.
With this patch, macro's arguments are read as the following:
"a,b" -> '("a" "b")
"a\,b" -> '("a,b")
"a\\,b" -> '("a\" "b")
"a\\\,b" -> '("a\,b")
"a\\\\,b" -> '(a"\\" "b")
Note that with the patch, you only need to escape backslashes before
a comma:
"a\\b\,c" -> '("a\\b,c")