Class names and id's for elements

[Guido1982]

It would help a lot (and I'm willing to write some code for this) if we'd have some more classnames and id's on elements. I'm thinking it's just a few additions to some TPL files, no harm done to the core. But this would help theme-wise to target certain elements with CSS and use icon fonts (which would reduce the number of files to be downloaded and make for better images). If you're willing to put this in the core repo, I'd be willing to propose some changes.