Allow multi-line "pvar list" strings

This directly improves avp_db_query() and cache_raw_query(),
allowing the following (notice param #2):

    avp_db_query("
        SELECT
            table_name,
            table_version
        FROM
            version",
        "$avp(tn),
         $avp(tv)");

pvar.c

@@ -4449,7 +4449,7 @@ pvname_list_t* parse_pvname_list(str *in, unsigned int type)
 	p = in->s;
 	while(is_in_str(p, in))
 	{
-		while(is_in_str(p, in) && (*p==' '||*p=='\t'||*p==','||*p==';'))
+		while(is_in_str(p, in) && (is_ws(*p)||*p==','||*p==';'))
 			p++;
 		if(!is_in_str(p, in))
 		{