ox-md.el: Add export-block

* ox-md.el (org-md-export-block): New function.
(md): Use it.
ox-md: Add support for MD, MARKDOWN keywords

* lisp/ox-md.el (org-md-keyword): New function.
(org-md-export-block): Allow "MARKDOWN" blocks.
ox-md: Handle HTML export blocks

* lisp/ox-md.el (org-md-export-block): Handle HTML export blocks.
Backport changes from Emacs r115870

* org.texi (Include files, The Export Dispatcher)
(Advanced configuration)
(Header arguments in Org mode properties): Spelling fixes.
Revert "Update copyright years."

This reverts commit 21105594fcb69fb4e1d636f4070fd25c86efbe35.
Update copyright year for files changed since 2013
Merge branch 'maint'

Conflicts:
	contrib/lisp/org-favtable.el
Delete org-favtable.el
ob-gnuplot.el (org-babel-gnuplot-quote-tsv-field): Fix code typo

* ob-gnuplot.el (org-babel-gnuplot-quote-tsv-field): Fix code typo.

TINYCHANGE
Merge branch 'maint'
org.el (org-set-tags): Ignore invisible text when restoring cursor position

* org.el (org-set-tags): Ignore invisible text when restoring
cursor position.
Merge branch 'maint'
ox: Change meaning of `org-export-with-\(table\|fixed-width\)

* lisp/ox.el (org-export-with-fixed-width, org-export-with-tables):
  Change docstring to reflect new meaning.
(org-export--skip-p): Completely ignore tables and fixed-width areas
if appropriate option is nil.
* testing/lisp/test-ox.el (test-org-export/handle-options): Add tests.
org-element: Fix parsing orphaned affiliated keywords

* lisp/org-element.el (org-element-keyword-parser): Fix parsing
  orphaned affiliated keywords.
org-element: Change data structure for cache

* lisp/org-element.el (org-element-at-point, org-element-cache-get,
  org-element-cache-put, org-element--cache-sync): Complete rewrite to
  use new data structure.
(org-element-context, org-element-cache-reset): Slight change in order
to use new tools to access cached data.
(org-element-cache-merge-changes-threshold): Renamed from
`org-element--cache-merge-changes-threshold'.
(org-element-cache-sync-idle-time): Renamed from
`org-element--cache-sync-idle-time'.
(org-element--cache-objects): New variable.

Now elements are stored in AVL tree and objects in a hash table.  Also
moved functions relative to cache into a specific section of the file.
Backport change from Emacs r115884
Merge branch 'maint'
Backport spelling fixes from Emacs r115885

* org-clock.el (org-clock-cancel-hook)
(org-clock-leftover-time): Fix typo in docstring.
Merge branch 'maint'
org.texi (Global and local cycling): Mention C-u C-u TAB

* org.texi (Global and local cycling): Mention C-u C-u TAB.

Thanks to François Pinard for suggesting this.