Add Marlin firmware. Has initial configuration for CoreXY and 1 servo.

Update CAD file with improved clearances for Pilot G2 cartridge clearances after first print.

Marlin Firmware/buildroot/tests/SAMD51_grandcentral_m4

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+#
+# Build tests for Adafruit Grand Central M4 (ATMEL ARM Cortex-M4)
+#
+
+# exit on first failure
+set -e
+
+#
+# Build with the default configurations
+#
+restore_configs
+opt_set MOTHERBOARD BOARD_AGCM4_RAMPS_144 SERIAL_PORT -1 \
+        TEMP_SENSOR_0 11 TEMP_SENSOR_BED 11 \
+        X_DRIVER_TYPE TMC2209 Y_DRIVER_TYPE TMC2209 Z_DRIVER_TYPE TMC2209 Z2_DRIVER_TYPE TMC2209 E0_DRIVER_TYPE TMC2209 \
+        RESTORE_LEVELING_AFTER_G28 false \
+        LCD_LANGUAGE it \
+        SDCARD_CONNECTION LCD \
+        NUM_Z_STEPPER_DRIVERS 2 \
+        HOMING_BUMP_MM '{ 0, 0, 0 }'
+opt_enable ENDSTOP_INTERRUPTS_FEATURE S_CURVE_ACCELERATION BLTOUCH Z_MIN_PROBE_REPEATABILITY_TEST \
+           FILAMENT_RUNOUT_SENSOR G26_MESH_VALIDATION MESH_EDIT_GFX_OVERLAY Z_SAFE_HOMING \
+           EEPROM_SETTINGS NOZZLE_PARK_FEATURE SDSUPPORT SD_CHECK_AND_RETRY \
+           REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER Z_STEPPER_AUTO_ALIGN ADAPTIVE_STEP_SMOOTHING \
+           STATUS_MESSAGE_SCROLLING LCD_SET_PROGRESS_MANUALLY SHOW_REMAINING_TIME USE_M73_REMAINING_TIME \
+           LONG_FILENAME_HOST_SUPPORT SCROLL_LONG_FILENAMES BABYSTEPPING DOUBLECLICK_FOR_Z_BABYSTEPPING \
+           MOVE_Z_WHEN_IDLE BABYSTEP_ZPROBE_OFFSET BABYSTEP_ZPROBE_GFX_OVERLAY \
+           LIN_ADVANCE ADVANCED_PAUSE_FEATURE PARK_HEAD_ON_PAUSE MONITOR_DRIVER_STATUS SENSORLESS_HOMING \
+           SQUARE_WAVE_STEPPING TMC_DEBUG EXPERIMENTAL_SCURVE
+exec_test $1 $2 "Build Grand Central M4 Default Configuration" "$3"
+
+# clean up
+restore_configs