Implemented 'Ping' and 'Pong' activities.

According to https://humungus.tedunangst.com/r/honk/v/tip/f/docs/ping.txt

1 files changed, 14 insertions, 0 deletions

diff --git a/main.c b/main.c
index 6a0bb74..b8fc97b 100644
--- a/main.c
+++ b/main.c
@@ -30,6 +30,7 @@ int usage(void)
     printf("actor {basedir} {uid} {url}      Requests an actor\n");
     printf("note {basedir} {uid} {'text'}    Sends a note to followers\n");
     printf("resetpwd {basedir} {uid}         Resets the password of a user\n");
+    printf("ping {basedir} {uid} {actor}     Pings an actor\n");
 
     return 1;
 }
@@ -228,6 +229,19 @@ int main(int argc, char *argv[])
         return 0;
     }
 
+    if (strcmp(cmd, "ping") == 0) {
+        xs *msg = msg_ping(&snac, url);
+
+        enqueue_output_by_actor(&snac, msg, url, 0);
+
+        if (dbglevel) {
+            xs *j = xs_json_dumps_pp(msg, 4);
+            printf("%s\n", msg);
+        }
+
+        return 0;
+    }
+
     if (strcmp(cmd, "request") == 0) {
         int status;
         xs *data = NULL;