ob-processing.el: Support for Processing language

ob-processing.el: Support for Processing language

* lisp/ob-processing.el: New file.

* doc/org.texi (Languages): Signal new language.

This library implements necessary functions for implementing editing
of Processing code blocks, viewing the resulting sketches in an
external viewer, and HTML export of the sketches.

Editing Processing blocks requires processing2-emacs mode. Viewing
Processing blocks embedded in Org buffer in an external viewer also
requires processing2-emacs. This viewing is bound to C-c C-v C-k and
produces no results in Org buffer. HTML export of the results of a
Processing block is also supported, assuming that the processing.js
module is available: the sketch is then drawn by the browser when the
HTML page is viewed. This drawing is implemented by embedding the
Processing code in a script using the processing.js module. The user
is responsible for making sure that processing.js is available in the
correct location.

Console output from a Processing block produced e.g. by println() is
shown in the Processing compilation window when the code is executed
in Org buffer, and in text area (console) of the browser when the code
is embedded in HTML.