fix spelling in API docu, command reply, logging, descriptions

sections: ctrl, gb, gsm, vty

Change-Id: Iac211b5cd8504da36b699777b95a2448dd7c3e70
diff --git a/src/ctrl/control_if.c b/src/ctrl/control_if.c
index f49d639..d2eb3e9 100644
--- a/src/ctrl/control_if.c
+++ b/src/ctrl/control_if.c
@@ -269,7 +269,7 @@
 err:
 	if (!cmd->reply) {
 		if (ret == CTRL_CMD_ERROR) {
-			cmd->reply = "An error has occured.";
+			cmd->reply = "An error has occurred.";
 			LOGP(DLCTRL, LOGL_NOTICE,
 			     "%s: cmd->reply has not been set (ERROR).\n",
 			     cmd->variable);