org-pcomplete: Remove spurious white spaces in block completion

* lisp/org-pcomplete.el (pcomplete/org-mode/file-option): Remove
  spurious white spaces, excepted for source blocks' opening string.
  Small refactoring.
Merge branch 'maint'
ox-freemind: Fix code typo

* contrib/lisp/ox-freemind.el (org-freemind--build-node-contents): Fix
  code typo.