add example measuring script

examples2/aql/measurements.aql

+begin
+  declare auto $a = 10;
+  start overall measurement frame Overall;
+  while ( -- $a ) do begin
+    execute expression stringology::exact::BoyerMooreHorspool ( "aaa", "a" );
+  end
+  stop measurement frame;
+  show measurements as tree;
+end