Update Makefile again to use the GDSes directly

gds/gen_caravel.tcl

diff --git a/gds/gen_caravel.tcl b/gds/gen_caravel.tcl
new file mode 100644
index 0000000..897579b
--- /dev/null
+++ b/gds/gen_caravel.tcl
@@ -0,0 +1,35 @@
+drc off
+gds readonly true
+gds rescale false
+
+gds read chip_io.gds
+
+gds read gpio_control_block.gds
+
+gds read mgmt_protect.gds
+
+gds read simple_por.gds
+
+gds read digital_pll.gds
+gds read DFFRAM.gds
+gds read mgmt_core.gds
+
+gds read storage.gds
+
+gds read user_id_programming.gds
+
+# Your project goes aboard here
+gds read user_project_wrapper.gds
+
+load ../mag/caravel.mag -dereference
+property GDS_FILE ""
+property GDS_START ""
+property GDS_END ""
+
+save caravel_out
+
+select top cell
+
+# cif *hier write disable
+
+gds write caravel_out.gds