Rational HMC monomial for non-degenerate twisted mass doublet

This is an implementation of a RHMC monomial for the non-degenerate twisted mass doublet. Its not yet to pull in, but I opened this pull request rather for discussion. The new input monomial is

    BeginMonomial NDRAT
      Timescale = 1
      kappa = 0.170
      AcceptancePrecision =  1e-20
      ForcePrecision = 1e-12
      StildeMin = 0.013577
      StildeMax = 3.096935
      Name = ndrat
      DegreeOfRational = 12
      Cmin = 0
      Cmax = 11
      ComputeEVFreq = 1
      2KappaEpsBar = 0.0935
      2Kappamubar = 0.1105
    EndMonomial

`Cmin` and `Cmax` is the range of terms in the rational to be included in this monomial. This allows frequency splitting by distributing the same rational approxmiation over many timescales. `StildeMin` (`StildeMax`) is the minimal (maximal) eigenvalue of the squared even/odd preconditioned nd twisted Dirac operator. (see the documentation for details)

I have added a second new monomial

    BeginMonomial NDRATCOR
      Timescale = 1
      kappa = 0.170
      AcceptancePrecision =  1e-20
      ForcePrecision = 1e-12
      StildeMin = 0.013577
      StildeMax = 3.096935
      Name = ndratcor
      DegreeOfRational = 6
      ComputeEVFreq = 1
      2KappaEpsBar = 0.0935
      2Kappamubar = 0.1105
    EndMonomial

which has no derivative part, but corrects for the approximation errors in the rational. Currently, I decided to go for this option rather than a reweighting factor, as all our analysis codes are probably written without reweighting factor. However, implementing a reweighting factor is now very easy.

There are now also corresponding clover monomials `NDCLOVERRAT` and `NDCLOVERRATCOR` monomials, the only difference to `NDRAT` and `NDRATCOR` being the additional `CSW` parameter.

As far as I could test, everything is working now as expected. I get identical results to our `NDPOLY` monomial. Also the splitting works. Currently running with `NDCLOVERRAT` to check.