Provide the ability to set settings in theme's configuration page

I think a interface would be more easy for users. Anyway themes can change this settings in the template.php files http://drupal.org/node/177868

#887074: Using a more flexible JS selector for block title remove the possibility to set the selector. It's not a problem because now we accept all h* tag. But some themes perhaps want to use a div instead of h1, h2, h... So I want this settings back but in a maintainable way. Collapsiblock look in is own folder theme it's also hard to update the module #750738: Load [themename].inc files from themes' directories, not collapsiblock's own directory.

#446930: additional theme parameters we need also more settings than just the title. We need:
* block selector
* title selector
* block content selector