Need some PHP schoolin’! passing var to url and the old options table

PHP (as usual) has some nifty stuff, namely http_build_query() for putting together URL requests.

However for some reason (historically) PHP4 compatibility and encoding issues currently WP maintains fork of that function internally and offers build_query() wrapper, as well as nifty higher level function for URL manipulation add_query_arg() and remove_query_arg().