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/STM32F103RC_fysetc

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+#
+# Build tests for STM32F103RC FYSETC
+#
+
+# exit on first failure
+set -e
+
+#
+# Build with the default configurations
+#
+use_example_configs "Creality/Ender-3/FYSETC Cheetah 1.2/base"
+exec_test $1 $2 "Cheetah 1.2 Configuration" "$3"
+
+# clean up
+restore_configs