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/ctrl_if.py b/python/trx/ctrl_if.py
index 1a7c0c3..d7e14f1 100644
--- a/python/trx/ctrl_if.py
+++ b/python/trx/ctrl_if.py
@@ -22,7 +22,7 @@
 # with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
-from udp_link import UDPLink
+from .udp_link import UDPLink
 
 class CTRLInterface(UDPLink):
 	def handle_rx(self, data, remote):