added hex generating script and set bf_weights init to UNUSED for g_sim

applications/lofar2/libraries/sdp/src/python/sdp_hex.py

...ons/lofar2/libraries/sdp/src/vhdl/node_sdp_beamformer.vhd

...ons/lofar2/libraries/sdp/src/vhdl/node_sdp_filterbank.vhd