Refactor the 'TRX Burst Interface' block

The following changes were made:

  - Both implementation and headers were merged with misc_utils
  - Fixed namespace mess: was gr::grgsm, became gr::gsm
  - More accurate class name was chosen: "trx_burst_if"
diff --git a/lib/misc_utils/CMakeLists.txt b/lib/misc_utils/CMakeLists.txt
index 81f2ca8..370f11c 100644
--- a/lib/misc_utils/CMakeLists.txt
+++ b/lib/misc_utils/CMakeLists.txt
@@ -34,5 +34,7 @@
     tmsi_dumper_impl.cc
     time_spec.cc
     fn_time.cc
+    udp_socket.cc
+    trx_burst_if_impl.cc
 )