Make DECSCUSR thickness configurable

config.def.h

@@ -41,6 +41,11 @@ static unsigned int actionfps = 30;
  */
 static unsigned int blinktimeout = 800;
 
+/*
+ * thickness of underline and bar cursors
+ */
+static unsigned int cursorthickness = 2;
+
 /*
  * bell volume. It must be a value between -100 and 100. Use 0 for disabling
  * it