changed threading (acqusition is slot based). removal of eNB_thread. timing all based on received timestamp.

added lte-enb.c which extracts all enb-specific code from lte-softmodem. corrects merge from develop branch in dlsch_modulations.c. removal of HW-specific code in lte-softmodem.c

usrp_lib: setting master clock rate to 30.72 and filter to 20MHz for all cases to improve noise figure and channel response

UHD interfacing (master clock 30.72, bandwidths on 5/10/20 @ 20 MHz), RX gain calibration back to normal.

bugfixing for UL. Remaining problems: CCE allocations in subframe 5 lead to occasional illegal DCI allocations (affects UL DCI which is missed by UE). waveform compliance with CQI in ULSCH.