alt_decoder.c
Decoding and calculating lag profiles. Data vector zero-padded on lower edge of
range. Can work with fractional lags.
Layout of parameter file:
Line	Name		Notes
0	nbits		Number of bits in the code
1	nr_ipp		Total number of subcycles in one integration period
2	vec_len		Number of samples per subcycle
3	nfract		Number of samples per code bit
4	nlags		Max lag (in samples)
5	sub_int		Number of sub-intervals in the sample vector, normally 1
6	nr_code_sets	Number of different subsets in the code
If negative:		Calculate slices. One slice contains nr_code_sets
			subcycles
>6			The code, number of lines = nbits*nr_code_sets

Number of lines: 7+nbits*nr_code_sets

Output:
For fractionality 2: [lag 1, lag 2, lag 3(1), lag 3(2), lag 4, lag 5(1),
	lag 5(2), lag 6, ... lag nfract(1), lag nfract(2)]
For fractionality 3: [lag 1, lag 2, lag 3, lag 4(1), lag 4(2), lag 5(1),
	lag 5(2), lag 6, lag7(1) lag 7(2), lag 8(1), lag 8(2), lag 9, ...
	lag nfract(1), lag nfract(2)]
...and so on.