Add a list of actions to the website

[Sewi]

tools/actions_list.pl could output a HTML file containing all the actions known to Padre.

This should be placed in the documentation section on padre.perlide.org and as soon as more and more actions get comments, it will be a good reference for Padre's features.

The HTML templates used for outputting should be reviewed before and maybe someone wants to add a output formatter for Padre's Template::Toolkit.