[development] PHP input format -> syntax checking

[Moshe Weitzman]

> Currently Drupal just has a stern warning that messing with the PHP
> code for a block can really mess up your site.  Two other possible
> solutions are the aforementioned javascript drupal_eval check OR using
> previews for any page that has a php input format.  Using javascript
> has the drawback of not working for all browsers.  Previews have the
> drawback of being relatively slow/painful.  I'm not sure there's
> really a better solution than the one we've got (stern warnings).

you can do a syntax check and not eval the code: php -l is the command line 
way. there is probably a non command line way. i don't like actually running 
the code via ajax or preview since the code might actually DO something.