Moved sort_pdkfiles.py to common/, and modified behavior to always use the
default sort (which is a natural sort), given that doing "glob.glob" on a
file directory results in a pretty arbitrary and meaningless ordering.
diff --git a/sky130/Makefile.in b/sky130/Makefile.in
index 88ad096..9525d38 100644
--- a/sky130/Makefile.in
+++ b/sky130/Makefile.in
@@ -73,7 +73,7 @@
 # This Makefile contains bash-isms
 SHELL = bash
 
-REVISION    = 20200508
+REVISION    = 20200927
 TECH        = sky130
 
 # If EF_STYLE is set to 1, then efabless naming conventions are