fix paging behaviour

* back to page 1 when using facets
* register arguments for PageBrowser View Helper
* do not attach query elements to the pager URLs (they seem to be present automatically)
rename paging paramter from »offset« to »page«

Now how do we get tx_pagebrowse to create a 1-based numbering in links?
more consistent handling of blank query field

make it the same as calling the page with no query