Sanitize link encoding
* lisp/org.el (org-store-link): Improve docstring.
(org-make-link-string): Escape internal links only when absolutely
necessary.
(org-link-escape-chars): Add percent character.
(org-link-escape-chars-browser): Make space character more visible.
(org-link-escape): Refactor code.
(org-display-inline-images): Properly unescape path before creating
the link.
(org-extract-attributes): Remove function.
* lisp/ox.el (org-export-resolve-fuzzy-link): Decode path before
resolving link.
* testing/lisp/test-ox.el (test-org-export/resolve-fuzzy-link): Add
test.