add a filter to loggers

events are accepted by the logger if the filter accepts them
the filter is optional (no filter means to accept all events)

common/utils/T/tracer/logger/textlog.c

@@ -4,6 +4,7 @@
 #include "database.h"
 #include "view/view.h"
 #include "utils.h"
+#include "filter/filter.h"
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ -42,6 +43,9 @@ static void _event(void *p, event e)
   char tt[64];
 #endif
 
+  if (l->common.filter != NULL && filter_eval(l->common.filter, e) == 0)
+    return;
+
   l->o.osize = 0;
 
 #ifdef T_SEND_TIME