Accept BigInt as input format

[dtamayo-nlp]

Thank @wildart for driving this forward.

I only have a quick comment. I was testing this algorithm for big matrices and I found the necessity of using the BigInt format to avoid a "DivideError: integer division error" in line 12 of bezout.jl (click Issue for more information).

The problem was that this format is not accepted in your code because "there is no method matching typemax(::Type{BigInt})". I have adapted the use of "typemax" in one part of the code to accept it.

I hope you find it useful.

[thchr]

It would be more meaningful to just change this to rsize = typemax(eltype(eachindex(M))), since the count below anyway will return something that references positions in the array.