mark view helpers and generated javascript code as html_safe
More view fixes; html_safe
Various XSS fixes

* page.rb: Escaping snippets/layouts
* standard_tags.rb: r:link
* radius_patch.rb: Override radius to ensure tag.expand is html_safe
* lib/radiant/taggable.rb: escape all tags
html_safe for configuration
Fix r:breadcrumbs
Require rails_xss in gemspec
Add missing html_safe calls and remove them where possible