ONOS-6257: fixing Region-peer-location function...

- corrected UiRegion.isRoot() implementation
- added to/from-compact-strings for LayoutLocation, so we can encode
   a list of them in an annotation
- Fixed bug in DistributedRegionStore which was emiting events that
   had a null region as subject.

Change-Id: I547e0c7f62385b85b191b8d63e6b569196623b84
diff --git a/tools/test/topos/regions-europe.sh b/tools/test/topos/regions-europe.sh
index 8f4790a..58f2944 100755
--- a/tools/test/topos/regions-europe.sh
+++ b/tools/test/topos/regions-europe.sh
@@ -16,7 +16,7 @@
 
 
 ## unfortunately, it takes a time for the sim to start up
-#  this is not ideal...
+#  this is not ideal... but we'll live with it for now
 
 echo
 echo "Sleeping while sim starts up... (${sleepfor} seconds)..."
@@ -111,7 +111,6 @@
 null-create-link direct Leeds Warrington
 
 # -- UK Peers
-## TODO: figure out why this data isn't getting put into runtime config?!
 region-add-peer-loc rUK rES 50.4060  -3.3860
 region-add-peer-loc rUK rFR 50.4060  -1.8482
 region-add-peer-loc rUK rIT 50.4060  -0.1361