Match XTerm (and presumably VT) behaviour on TAB in last column.

src/conio/cterm.txt

@@ -40,11 +40,7 @@ Control characters:
 0x09 - HT:
 	Moves to the next horizontal tab stop.  Does not overwrite
 	any characters in between.  If the starting position is
-	last column, advances to next line.  If starting
-	position is the last column of the last line, performs
-	a scroll, filling the new line at bottom with the
-	current attribute and moves to the first character in
-	the new line.
+	last column, cursor does not move.
 
 0x0A - LF:
 	Move cursor position to same column of the next row.