[ticket/12347] Move breadcrumb seperator from template to CSS

I had to remove some of the white-spaces, because it will introduce weird gaps/spacing when displaying inline-blocks.

It seems to work fine with the responsive breadcrumbs script. The bidi.css might need some work (although it works fine in general), but the bidi.css needs overall work. There are other issues that need to be solved first.

PHPBB3-12347