Fix spelling errors

@@ -953,7 +953,7 @@ com_info (char *arg)
 
   if (!printed)
     {
-      printf ("No commands match `%s'.  Possibilties are:\n", arg);
+      printf ("No commands match `%s'.  Possibilities are:\n", arg);
 
       for (i = 0; commands[i].name; i++)
 	{

@@ -49,7 +49,7 @@ imap4d_uid (struct imap4d_session *session,
     rc = imap4d_search0 (tok, 1, &err_text);
   else
     {
-      err_text = "Uknown uid command";
+      err_text = "Unknown uid command";
       rc = RESP_BAD;
     }
   return io_completion_response (command, rc, "%s %s", cmd, err_text);

@@ -121,7 +121,7 @@ struct mailvar_symbol mailvar_tab[] =
       N_("input message is terminated with a dot alone on a line") },
     { { "editheaders", },
       MAILVAR_TYPEMASK (mailvar_type_boolean),
-      N_("allow to edit message headers while composing") },
+      N_("allow editing message headers while composing") },
     { { "emptystart", },
       MAILVAR_TYPEMASK (mailvar_type_boolean),
       N_("start interactive mode if the mailbox is empty") },

@@ -226,7 +226,7 @@ shell_help (int argc, char **argv)
 	print_comtab (mu_strout, com);
       else
 	{
-	  mu_printf ("No commands match `%s'.  Possibilties are:\n", name);
+	  mu_printf ("No commands match `%s'.  Possibilities are:\n", name);
 	  list_commands (shell_comtab, name);
 	}
     }