tangle checks for COMMENT in parent headlines

* lisp/ob-tangle.el (org-babel-under-commented-heading-p): Check if
  the point is under a commented heading (including parents).
  (org-babel-tangle-collect-blocks): Don't tangle blocks is under a
  commented heading (including parents).
export back-ends: Remove duplicate information

* lisp/ox-ascii.el: Remove comments at the beginning of the file since
  the library is documented in Org manual.
* lisp/ox-beamer.el: Remove comments at the beginning of the file since
  the library is documented in Org manual.
* lisp/ox-html.el: Remove comments at the beginning of the file since
  the library is documented in Org manual.
* lisp/ox-icalendar.el: Remove comments at the beginning of the file since
  the library is documented in Org manual.
* lisp/ox-md.el: Remove comments at the beginning of the file since
  the library is documented in Org manual.
Merge branch 'maint'
org-element: Do not retrieve Babel related info

* lisp/org-element.el (org-element-babel-call-parser,
  org-element-inline-babel-call-parser): Do not call
  `org-babel-lob-get-info' since it is out of parser's scope.
(org-element-babel-call-interpreter,
org-element-inline-babel-call-interpreter): Apply changes to parsers.
fix typo in `org-babel-under-commented-heading-p'

    Thanks to Alan Schmitt for pointing this out.

* lisp/ob-tangle.el (org-babel-under-commented-heading-p): Fix name
  typo.
ob-ruby.el: fix result of :results output :session combination.

* lisp/ob-ruby.el (org-babel-ruby-evaluate):
  set conf.echo=false for the duration of evaluation.

* testing/lisp/test-ob-ruby.el (test-ob-ruby/session-output): new test.
ox-taskjuggler: Fix effort property

* contrib/lisp/ox-taskjuggler.el (org-taskjuggler--build-task): Fix
  effort property if `org-effort-property' was changed.
Merge branch 'maint'
ox-odt: Stop adding leading space after line break

* lisp/ox-odt.el (org-odt-line-break, org-odt-plain-text): Remove
newline after line-break tag.

The exporter was pretty-printing the ODT XML with newlines after
forced line breaks, but LibreOffice would interpret those as
spaces.  This led to a leading space after every manual line break.
Merge branch 'maint'
org.texi: Improve Beamer export documentation

* doc/org.texi (Beamer export): Be more accurate about BEAMER_OPT
  property.
org.texi: Remove reference to quoted underscores

* doc/org.texi (Subscripts and superscripts): Remove reference to
  quoted underscores until this mechanism is implemented again.
Merge branch 'maint'
org-element: Use `org-latex-regexps', not `org-format-latex-options'

* lisp/org-element.el (org-element-latex-or-entity-successor,
  org-element-latex-fragment-parser): Use `org-latex-regexps' instead
  of `org-format-latex-options'.
* testing/lisp/test-org-element.el: Fix tests.

`org-latex-regexps' defines the correct syntax for LaTeX code within
an Org buffer.  On the other hand, `org-format-latex-options'
determines which syntax can be previewed within the buffer.
Merge branch 'maint'
Add ebnf support to babel.
ox-latex: Fix docstring

* lisp/ox-latex.el (org-latex-listings-options): Use correct number of
  backslash characters in the example.

Reported-by: Thomas S. Dye <tsd@tsdye.com>
Merge branch 'maint'
ox-latex: Add \endfirsthead to longtable export

* lisp/ox-latex.el (org-latex-table-row): Implements the \endfirsthead
command so the caption only appears once, at the top of the table.
Subsequent pages of the table start with "Continued from previous
page".
ox-latex: Longtable continuation strings customizable

* lisp/ox-latex.el (org-latex-longtable-continued-on,
  org-latex-longtable-continued-from): New variables.
(org-latex-table-row): Use new variables.