#1395320 by dereine: Allow to use list human readable values instead of only machine key in argument summaries

#1137892 by agentrickard: Provide an area handler which allows to use some tokens(items per page, etc.) in the header/footer.

by dereine: Improve filter term_node by defining all used variables, removed unused variables and document much more stuff.

#1301366 by dereine: Add a node_comment_statistics::last_comment_uid field, filter, argument and relationship