Introduction - If you have any usage issues, please Google them yourself
Outputs minimum-redundancy length-limited code bitlengths for symbols with the
given counts. The bitlengths are limited by maxbits.
The output is tailored for DEFLATE: symbols that never occur, get a bit length
of 0, and if only a single symbol occurs at least once, its bitlength will be 1,
and not 0 as would theoretically be needed for a single symbol.
frequencies: The amount of occurances of each symbol.
n: The amount of symbols.
maxbits: Maximum bit length, inclusive.
bitlengths: Output, the bitlengths for the symbol prefix codes.
return: 0 for OK, non-0 for error.