org.el: Fix setting and deleting properties with a null value

* org.el (org-property-re): Also match null properties by
default.
(org-entry-delete): Also delete null properties.
(org-read-property-value): Allow the empty string as a new
value.
(org-delete-property): Throw a message when there is not
property to delete.

Thanks to Andrea Rossetti for reporting this.
Merge branch 'maint'

Conflicts:
	lisp/org.el
org-agenda.el (org-agenda-custom-commands-local-options): Fix misquoted values

* org-agenda.el (org-agenda-custom-commands-local-options):
Fix misquoted values.

Thanks to Thomas Morgan for reporting this.
Merge branch 'maint'
Makefile: remove empty line in help output

* Makefile (help helpall): Remove empty line in help output.
mk/server.mk: add testing/ directory to distribution tarball

* mk/server.mk (ORGFULL): Add testing/ directory to distribution
  tarball.
Merge branch 'maint'
testing/lisp/test-org: actually check that org-open-at-point did the right thing

* testing/lisp/test-org.el (test-org/open-at-point): The test should
  leave the cursor one line above "Org Mode Manual" in the "*info*"
  buffer.  Try to switch to that buffer and check that point is where
  it should be, then kill the buffer.
testing/lisp/test-org.el: Update tests

* testing/lisp/test-org.el
(test-org/open-at-point-in-property): Rename from
`test-org/open-at-point'.  Only test whether
`org-open-at-point' does not throw an error.
(test-org/open-at-point-in-comment)
(test-org/open-at-point/info): New tests.
.gitignore: Ignore ChangeLog files
ox: Fix priority bug in :title property

* lisp/ox.el (org-export--get-inbuffer-options): Return the empty
  string instead of nil when TITLE keywords has no value.
(org-export--get-buffer-attributes): Do not set :title property
early.
(org-export--get-global-options): Do not ignore anymore nil values.
Small refactoring.
(org-export-as): Correctly set :title here.

Thanks to Nicolas Richard for reporting it.
http://permalink.gmane.org/gmane.emacs.orgmode/87149
Merge branch 'maint'

Conflicts:
	lisp/ox.el
Fix typo

* lisp/org.el (org-scan-tags): Fix typo in docstring.
Merge branch 'maint'
Remove useless code
TODO in ob-exp.el
add options to LaTeX bibtex cite: links

* contrib/lisp/ox-bibtex.el (org-bibtex-merge-contiguous-citations):
  Add the ability to specify options so that for example the following
  link "[[cite:(Chapter 2)foo]]" will be converted to the following
  LaTeX "\cite[Chapter 2](foo)".
when present resolve orig-buffer headlines w/IDs

* lisp/ob-exp.el (org-babel-exp-in-export-file): Instead of using the
  headline text use the headline ID when one is present.  This fixes a
  bug in the resolution of code block headers in properties during
  export when multiple headlines with the same name are present.
generate intermediate EPS on ditaa pdf generation

TINYCHANGE

* lisp/ob-ditaa.el (org-babel-execute:ditaa): When generating a pdf,
  ensure that an intermediate EPS file is generated first.
un-duplicate ditaa eps file name generation

* lisp/ob-ditaa.el (org-babel-execute:ditaa): Un-duplicate ditaa eps
  file name generation.