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/__init__.py b/python/trx/__init__.py
index c8bddbe..23042b0 100644
--- a/python/trx/__init__.py
+++ b/python/trx/__init__.py
@@ -20,10 +20,10 @@
 This is a set of helper classes for the grgsm_trx application.
 '''
 
-from udp_link import UDPLink
-from ctrl_if import CTRLInterface
-from ctrl_if_bb import CTRLInterfaceBB
-from radio_if import RadioInterface
-from transceiver import Transceiver
+from .udp_link import UDPLink
+from .ctrl_if import CTRLInterface
+from .ctrl_if_bb import CTRLInterfaceBB
+from .radio_if import RadioInterface
+from .transceiver import Transceiver
 
-from dict_toggle_sign import dict_toggle_sign
+from .dict_toggle_sign import dict_toggle_sign