ox: Improve speed wrt table export

* lisp/ox.el (org-export-resolve-fuzzy-link): Change property name
  holding cache.
(org-export-table-has-header-p, org-export-table-row-group,
org-export-table-cell-width, org-export-table-cell-alignment): Cache
results.
(org-export-table-cell-address): Refactor.
(org-export-get-parent): Inline function.
* testing/lisp/test-ox.el: Update tests.
ox-ascii: Improve speed wrt table export

* lisp/ox-ascii.el (org-ascii--table-cell-width): Cache results of
  this internal function since it is called at each cell, though its
  value only change column wise.
Merge branch 'maint'
org.texi: Correct syntax for exporting HTML fragments
org.texi: Fix joke
Merge branch 'maint'
Merge remote-tracking branch 'upstream/master' into latex-numbering