[babel] developments

["Eric Schulte" <schulte.eric@gmail.com>]

Hi,

Dan and I are releasing some accumulated developments.  They are
described below.  We hope to now turn towards improving the
documentation and test framework, as we've developed much of it into
obsolescence.

Best -- Eric

- org-babel can now cache the results of source block execution to avoid
  rerunning the same calculation.  The cache uses a sha1 hash key of the
  source code body and the header arguments to determine if
  recalculation is required.  These hash keys are kept mostly hidden in
  the #+resname line of the results of the block.  This behavior is
  turned off by default.  It is controlled through the :cache
  and :nocache header arguments.  To enable caching on a single block
  add the :cache header argument, to enable global caching change the
  value of your `org-babel-default-header-args' variable as follows

  (setq org-babel-default-header-args
        (cons '(:cache)
              (assq-delete-all :nocache org-babel-default-header-args)))

- It is now possible to fold results by tabbing on the beginning of the
  #+resname line.  This can be done automatically to all results on
  opening of a file by adding the following to your org-mode hook

  (add-hook 'org-mode-hook 'org-babel-result-hide-all)

- allow header argument values to be lisp forms, for example the
  following is now valid

  :file (format "%s/images/pca-scatter.png" dir)

- aliases
  - 'call' can now be used as an alias for 'lob'
  - 'results' can now be used as an alias for 'resname'
  - 'source' or 'function' can now be used as aliases for 'srcname'