Update to find ICE 3.5.

Added FindICE-3.5.cmake from gnuradio.

Updated CMakeLists.txt file to find ICE 3.5 and fallback to find
ICE (3.4) if it fails.

Updated es_queue to include the event type in the output when it
discards an event in fetch_next_event(...).
Fixed enabling GR_CTRLPORT.

The GR_CTRLPORT definition is now added properly when ICE < 3.5 is
found.
Merge pull request #2 from gr-sp/master

ICE 3.5 update