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/test-gcode/M808-loops.gcode

@@ -0,0 +1,16 @@
+;
+; M808 Repeat Marker Test
+;
+
+M808 L3 ; Marker at 54
+
+M118 Outer Loop
+M300 S220 P100
+
+M808 L5 ; Marker at 111
+
+M118 Inner Loop
+M300 S110 P100
+
+M808
+M808