closes #345410: two_lines_rset, two_cols_rset, two_etypes_rset are badly named replaced by multi_lines_rset, multi_columns_rset, multi_etypes_rset, all taking optional 'nb' argument allowing to specify and exact count. Bw compat is kept, usage of deprecated function updated in cw itself. Also drop custom at_least_two_columns selector (in views.plots) since it was the same as multi_columns_rset. Hopefuly the renaming will help in avoid such pb... We should now decide if we want to deprecate one_* selector in favor of multi_*(nb=1). See note on this at then end of selectors.py

/* tables */
/*table.tablesorter {
	font-family:arial;
	background-color: #CDCDCD;
	margin:10px 0pt 15px;
	font-size: 8pt;
	width: 100%;
	text-align: left;
} */

table.listing tr .headerSortUp {
  background-image: url(asc.gif);
}
table.listing tr .headerSortDown {
  background-image: url(desc.gif);
}
table.listing tr .headerSortDown, table.listing tr .headerSortUp {
   background-color: #DDD;
   background-repeat: no-repeat;
   background-position: center right;
}