Export and use aidset, set USE_TYPED_DSET

I did ai so I can use it as an example in the Release Notes.

modules/database/src/std/dev/devTimestamp.c

@@ -40,12 +40,9 @@ static long read_ai(aiRecord *prec)
     return 2;
 }
 
-struct {
-    dset common;
-    DEVSUPFUN read_write;
-    DEVSUPFUN special_linconv;
-} devTimestampAI = {
-    {6, NULL, initAllow, NULL, NULL}, read_ai,  NULL
+aidset devTimestampAI = {
+    {6, NULL, initAllow, NULL, NULL},
+    read_ai,  NULL
 };
 epicsExportAddress(dset, devTimestampAI);
 
@@ -72,6 +69,7 @@ struct {
     dset common;
     DEVSUPFUN read_stringin;
 } devTimestampSI = {
-    {5, NULL, initAllow, NULL, NULL}, read_stringin
+    {5, NULL, initAllow, NULL, NULL},
+    read_stringin
 };
 epicsExportAddress(dset, devTimestampSI);