ob-C: Add list support.
* lisp/ob-C.el (org-babel-C-var-to-C): Add list support
(org-babel-C-val-to-C-list-type, org-babel-C-val-to-C-type,
org-babel-C-format-val): New functions.
(org-babel-C-ensure-main-wrap, org-babel-execute:C,
org-babel-execute:C++, rg-babel-execute:cpp, org-babel-C++-compiler,
org-babel-C-compiler): Improve docstring.
* testing/examples/ob-C-test.org (string_var): Add required std::
(Array): Add missing ID.
(Matrix): Add tests for list support.
* testing/lisp/test-ob-C.el (ob-C/table): Test succeeds.
(ob-C/list-var, ob-C/vector-var, ob-C/list-list-var): Add tests for
list support.
Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>