FIX: This commit fixes the broken LF since I change the spindelay calls. The original problem is that spindelayus calls is incremented with21.3us each step, making it very hard to find exact timings found in the datasheets for T55x7, HID etcetc. When @marshmellow and I looked into this 2014, I had this on my back of my mind but forgot it since I didn't know how the source code / pm3 worked. This behavior in spindelayus has given the bit-period for ON/OFF measured in (us) very hard to find. Its kind of magic that it worked so far so good. Well until I started to look into the "hf legic" bitbanging ASK ON/OFF keying and that one needs a much more precis timer. Same goes for the PCF7931 code.
I've added a precise timer in the new files ticks.c and moved some older stuff from util.c to have a solid base for this.
UNTESTED, and the timings measured for t55x7 in lfops.c and other parts has not been adjusted to this "correct" timer.