Various python3 related changes

- Use relative import for grgsm's modules
- Convert map to list
- Remove the hier_block.py workaround as as gnuradio 3.7 is no longer
  supported in this branch

Change-Id: I5ca8fd340823996e8c444aaf18ddacd85c92ab1c
diff --git a/python/trx/radio_if_uhd.py b/python/trx/radio_if_uhd.py
index ef2e0ed..664a51c 100644
--- a/python/trx/radio_if_uhd.py
+++ b/python/trx/radio_if_uhd.py
@@ -24,7 +24,7 @@
 
 from gnuradio import uhd
 
-from radio_if import RadioInterface
+from .radio_if import RadioInterface
 
 class RadioInterfaceUHD(RadioInterface):
 	# Human-readable description