[Rest2web-develop] Added even more tests to validate.py...

[Nicola L. <ni...@te...>]

...and refined the mixed_list check.

-- 
Nicola Larosa - ni...@te...

Learning C after learning Python can be done via Pyrex. [...]
Learning Java after learning Python can be done via Jython. [...]
Learning Perl after learning Python can ... never mind. ;-)
 -- André Roberge, May 2005