Revert "#1235994 by das-peter, scor: Allow to group by field value instead of field html. This allows to use rdf with fields"

This reverts commit a0e16956.

Conflicts:

	plugins/views_plugin_style.inc

#1314306 by Hanno: Don't translate html-tags, because translators might get confused and the user should really see the original tag all the time.

#1090098 by dereine, chx: Convert database views which were defaulted in d6.2 and exported to views3. Sadly this only works for exported

#1235994 by das-peter, scor: Allow to group by field value instead of field html. This allows to use rdf with fields

 Now the conversion for the default case works automatically.
 Additional the code itself were simplified quite a lot and some comments
 got added.

#1302494 by defr: Don't alter the value_options directly for flatten the options in in_operator filter

#1109108 by szantog: Handler translation keys should use the id instead of the field to have a unique key for multiple fields

#1193742 by bojanz: Replace too hard css rule with a special check for the views-remove-checkbox class