More work on holes: added documentation and Postscript output.

- overlap.c (inside, test_overlap): check for instance type 
- overlap.c (inside, test_overlap): support hole instances
- README: put a pointer to the GUI description at the beginning
- README, gui.html: documented role and creation of holes
- inst.h: holes can now link to pads and vice versa
- hole.c, obj.c (instantiate): connect holes with pads and apply consistency 
  checks
- postscript.c: added output for holes
- icons/hole.fig: make hatched surroundings of hole look more round



git-svn-id: http://svn.openmoko.org/trunk/eda/fped@5940 99fdad57-331a-0410-800a-d7fa5415bdb3

obj.c

@@ -20,6 +20,7 @@
 #include "expr.h"
 #include "meas.h"
 #include "inst.h"
+#include "hole.h"
 #include "layer.h"
 #include "delete.h"
 #include "obj.h"
@@ -475,6 +476,8 @@ int instantiate(void)
 		activate_found();
 	find_vec = NULL;
 	find_obj = NULL;
+	if (ok)
+		ok = link_holes();
 	if (ok)
 		ok = refine_layers();
 	if (ok)