Creality Ender support.

Reverse engineered from the unpublished firmware from Creality,
inferring the base version and configuration they used. The basis is
the firmware version from "Jul 31 2017 10:16:30". Configurations were
found by seeing what code was compiled into the firmware, and
constants used there.

They used Marlin 1.0.1, because

* 1.0.0 had very different serial output in `setup()` and overall
  code structure.
* 1.0.2 changed the `VERSION_STRING` to include a leading space,
  and `lcd_init` uses `SET_INPUT` instead of `pinMode`.

For U8Glib, a version between 1.14 and 1.17 was used, because

* 1.12 didn't have the extra speed argument to u8g_InitCom.
* 1.13 didn't have the soft reset instruction for UC1701 initialization.
* 1.18 has a new directory structure.

Quirks

* The value of PID_dT hints that F_CPU is 20M, but MarlinSerial.begin
  suggests it's indeed 16M (and the board uses 16M). Left at 16M for now.

* The LED and DOGLCD_CS are on the same pin.

Marlin/pins_CREALITY_ENDER.h

@@ -0,0 +1,34 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/**
+ * Creality Ender pin assignments
+ *
+ * Applies to the following boards:
+ *
+ *  Creality Ender-2
+ *  Creality Ender-4
+ */
+
+#define BOARD_NAME "Creality Ender"
+
+#include "pins_SANGUINOLOLU_12.h"