Marlin-bugfix-2.0.x 11.4.2018

Description

Adding the second extruder to control different e-steps.

Marlin\src\HAL\HAL_LPC1768\../../inc/SanityCheck.h:1883:1: error: static assertion failed: DEFAULT_AXIS_STEPS_PER_UNIT has too many elements.
static_assert(COUNT(sanity_arr_1) <= XYZE_N, "DEFAULT_AXIS_STEPS_PER_UNIT has too many elements.");
^~~~~~~~~~~~~
Marlin\src\HAL\HAL_LPC1768\../../inc/SanityCheck.h:1884:1: error: static assertion failed: DEFAULT_MAX_FEEDRATE has too many elements.
static_assert(COUNT(sanity_arr_2) <= XYZE_N, "DEFAULT_MAX_FEEDRATE has too many elements.");
^~~~~~~~~~~~~
Marlin\src\HAL\HAL_LPC1768\../../inc/SanityCheck.h:1885:1: error: static assertion failed: DEFAULT_MAX_ACCELERATION has too many elements.
static_assert(COUNT(sanity_arr_3) <= XYZE_N, "DEFAULT_MAX_ACCELERATION has too many elements.");
[Marlin.zip](https://github.com/MarlinFirmware/Marlin/files/2546269/Marlin.zip)