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/include/grgsm/misc_utils/CMakeLists.txt b/include/grgsm/misc_utils/CMakeLists.txt
index 978695e..8ac1f52 100644
--- a/include/grgsm/misc_utils/CMakeLists.txt
+++ b/include/grgsm/misc_utils/CMakeLists.txt
@@ -34,6 +34,7 @@
     message_printer.h
     tmsi_dumper.h
     msg_to_tag.h
+    trx_burst_if.h
     controlled_fractional_resampler_cc.h 
     time_spec.h
     fn_time.h DESTINATION include/grgsm/misc_utils