Remove dependency on HaskellForMaths

[wchresta]

The dependency on HaskellForMaths turned out to be not a wise choice. Even though it provides an implementation of field extensions (finite fields with non-prime order), the implementation does not seem to be clean and not in the same spirit as linear-codes (e.g. reimplementation of GHC.TypeLits.Nat). Also, the library seems to be abandoned. There are two options:

• Create own implementation of field extensions, maybe even with optimisQed algorithms for 2^k
  • extending modular-arithmetic
  • extending finite-field
• Find an alternative existing library that is more suitable.

[wchresta]

Opened issue for extending finite-field: https://github.com/msakai/finite-field/issues/1

[Bodigrim]

Would not http://hackage.haskell.org/package/galois-field-1.0.1/docs/Data-Field-Galois.html#t:TowerOfFields fit the bill?