Add AprilTag dictionaries to be able to detect AprilTag markers. Add ArUco and AprilTag 2 citations.

also avoids manual memcpy: the predefined dictionary data is not
duplicated any more.

store marker internally as
"r0_b0, r0_b1, .. , r0_bn, r2_b0, .." instead of
"r0_b0, r1_b0, .. , rn_b0, r1_b0, .."
i.e. the same as in predefined_dictionaries.cpp.
This makes loading a dictionary a simple memcpy and also allows to get
rid of the custom hammingDistance implementation in favor of
hal::normHamming.