fix 'hf iclass sim'

* fix tag response timing. iClass differs from ISO15693 in this respect.
* speedup CodeIso15693AsTag()
* TransmitTo15693Tag(): don't send unmodulated start of SOF
* reduce modulation depth in hi_simulate.v
* calculate CRC for configuration block when simulating
* Show real response time instead of planned response time in 'hf list iclass'

fpga/hi_simulate.v

@@ -132,7 +132,7 @@ always @(*)
 // modulation than a real tag would.
 assign pwr_hi = 1'b0;                   // HF antenna connected to GND
 assign pwr_oe3 = 1'b0;                  // 10k Load
-assign pwr_oe1 = modulating_carrier;    // 33 Ohms Load
+assign pwr_oe1 = 1'b0;                  // 33 Ohms Load
 assign pwr_oe4 = modulating_carrier;    // 33 Ohms Load
 
 // This is all LF and doesn't matter