Add /pgp sendpub command

Command allows to share your PGP pub key with ease,
it's not described in XEP-0027, but used in some clients,
such as PSI, Pidgin.
Fix typos
Minor improvements

src/command/cmd_ac.c

@@ -910,6 +910,7 @@ cmd_ac_init(void)
     autocomplete_add(pgp_ac, "log");
     autocomplete_add(pgp_ac, "char");
     autocomplete_add(pgp_ac, "sendfile");
+    autocomplete_add(pgp_ac, "sendpub");
 
     pgp_log_ac = autocomplete_new();
     autocomplete_add(pgp_log_ac, "on");