Predicate error causes long response times

[kjoehass]

Trying to read a card on a Pi 0 can take almost one second, and this delay is unnecessary. The problem is an error in MFRC522.py at line 219:
if ~((i != 0) and ~(n & 0x01) and ~(n & waitIRq)):
This line is using bit-wise complement instead of the proper logical not. It should be written as
if not ((i != 0) and not (n & 0x01) and not (n & waitIRq)):
instead. This significantly reduces the time needed to read a card, or to detect that a card is not present.