fixing iso14443b (issue #103):

- fix: IQ demodulator (FPGA)
- fix: approximately align reader signal delay to tag response delay (FPGA)
- fix: remove deprecated RSSI calculation to improve decoder speed (iso14443b.c)
- fix: better approximation of signal amplitude to avoid false carrier detection (iso14443b.c)
- fix: remove initial power off in iso14443b raw command (iso14443b.c)
- add: enable tracing for iso14443b raw command (iso14443b.c)
- fix: client crashed when checking CRC for incomplete responses (iso14433b.c)
- speeding up snoop to avoid circular buffer overflow
- added some comments for better documentation
- rename functions (iso14443 -> iso14443b)
- remove unused code in hi_read_rx_xcorr.v