Make CR behavior respect left margin when vertical split mode is enabled.

xterm-cr-respect-leftmargin.diff

diff -rNU5 a/cursor.c b/cursor.c
--- a/cursor.c      2012-06-04 04:57:47.000000000 +0900
+++ b/cursor.c      2013-06-07 00:23:08.000000000 +0900
@@ -269,12 +269,14 @@
     int left = ScrnLeftMargin(xw);
     int col;
 
     if (xw->flags & ORIGIN) {
 	col = left;
-    } else if (screen->cur_col > left) {
-	col = left;
+    } else if (IsLeftRightMode(xw)) {
+	if (ScrnIsColInMargins(screen, screen->cur_col)) {
+	    col = left;
+	}
     } else {
 	/*
 	 * If origin-mode is not active, it is possible to use cursor
 	 * addressing outside the margins.  In that case we will go to the
 	 * first column rather than following the margin.