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.

Author: brammool

src/channel.c

@@ -1567,7 +1567,7 @@ invoke_callback(channel_T *channel, char_u *callback, partial_T *partial,
     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;

src/eval.c

@@ -270,7 +270,7 @@ eval_init(void)
 	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);

src/regexp_nfa.c

@@ -1359,7 +1359,7 @@ nfa_regatom(void)
 		    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 @@ check_char_class(int class, int c)
 
 	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 @@ nfa_regmatch(
 
 #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 @@ nfa_regcomp(char_u *expr, int re_flags)
     {
 	/* 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 */
     }
 

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    160,
 /**/
     159,
 /**/