patch 8.0.0160: EMSG() is sometimes used where it should be IEMSG()

Problem:    EMSG() is sometimes used for internal errors.
Solution:   Change them to IEMSG(). (Dominique Pelle)  And a few more.
diff --git a/src/channel.c b/src/channel.c
index 32f3527..f409e1d 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -1567,7 +1567,7 @@
     int		dummy;
 
     if (safe_to_invoke_callback == 0)
-	EMSG("INTERNAL: Invoking callback when it is not safe");
+	IEMSG("INTERNAL: Invoking callback when it is not safe");
 
     argv[0].v_type = VAR_CHANNEL;
     argv[0].vval.v_channel = channel;
diff --git a/src/eval.c b/src/eval.c
index 70fbc88..11fc035 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -270,7 +270,7 @@
 	p = &vimvars[i];
 	if (STRLEN(p->vv_name) > 16)
 	{
-	    EMSG("INTERNAL: name too long, increase size of dictitem16_T");
+	    IEMSG("INTERNAL: name too long, increase size of dictitem16_T");
 	    getout(1);
 	}
 	STRCPY(p->vv_di.di_key, p->vv_name);
diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index fcca818..919dadc 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -1359,7 +1359,7 @@
 		    rc_did_emsg = TRUE;
 		    return FAIL;
 		}
-		EMSGN("INTERNAL: Unknown character class char: %ld", c);
+		IEMSGN("INTERNAL: Unknown character class char: %ld", c);
 		return FAIL;
 	    }
 #ifdef FEAT_MBYTE
@@ -4925,7 +4925,7 @@
 
 	default:
 	    /* should not be here :P */
-	    EMSGN(_(e_ill_char_class), class);
+	    IEMSGN(_(e_ill_char_class), class);
 	    return FAIL;
     }
     return FAIL;
@@ -6688,7 +6688,7 @@
 
 #ifdef DEBUG
 		if (c < 0)
-		    EMSGN("INTERNAL: Negative state char: %ld", c);
+		    IEMSGN("INTERNAL: Negative state char: %ld", c);
 #endif
 		result = (c == curc);
 
@@ -7216,7 +7216,7 @@
     {
 	/* TODO: only give this error for debugging? */
 	if (post_ptr >= post_end)
-	    EMSGN("Internal error: estimated max number of states insufficient: %ld", post_end - post_start);
+	    IEMSGN("Internal error: estimated max number of states insufficient: %ld", post_end - post_start);
 	goto fail;	    /* Cascaded (syntax?) error */
     }
 
diff --git a/src/version.c b/src/version.c
index f1a36da..641c72c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    160,
+/**/
     159,
 /**/
     158,