Remove hard-coding of BCH polynomial

[cburkert]

The hard-coded polynomial was taken from bchlib's example. This limits the supported range of fuzziness thresholds and should rather be chosen dynamically based on the FCS parameters.

[cburkert]

Polynomial is made user-definable in 1621ea6

[Asrar-b]

Hi,
is this argument mean n in BCH(n,k,t)? or what does it mean?
Also, why I can't change the polynomial arg.? , an error arise while changing this arg,
"can't change this argument,bad parameter?

[cburkert]

@lolib11 The argument specifies which polynomial is used for the BCH code.
As you can see in the code, it is directly passed to bchlib. So I suggest you go there for more information about what are valid polynomials and how to select them.
https://github.com/jkent/python-bchlib