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/STM32F103VE_longer

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+#
+# Build tests for STM32F103VET6
+#
+
+# exit on first failure
+set -e
+
+use_example_configs Alfawise/U20
+opt_enable BAUD_RATE_GCODE
+exec_test $1 $2 "CLASSIC_UI U20 config" "$3"
+
+use_example_configs Alfawise/U20
+opt_enable BAUD_RATE_GCODE TFT_COLOR_UI
+opt_disable TFT_CLASSIC_UI CUSTOM_STATUS_SCREEN_IMAGE
+exec_test $1 $2 "COLOR_UI U20 config" "$3"
+
+use_example_configs Alfawise/U20-bltouch
+opt_enable BAUD_RATE_GCODE
+exec_test $1 $2 "BLTouch U20 config"
+
+# cleanup
+restore_configs