Find spots in a raw vector that match a given byte sequence.
matchBytes(input, b1, ...)
a vector of raw (byte) values.
a vector of bytes to match (must be of length 2 or 3 at present;
for 1-byte, use
additional bytes to match for (up to 2 permitted)
List of the indices of
input that match the start of the
bytes sequence (see example).