Extend RHMC to rational value of number of tastes (Feature #738)
At the moment num_tastes can be only an integer. It is physically interesting to use floating point values of it. One should then change a bit the code around, in particular:
- introduce a new parameter like num_tastes_decimal_digits that tells the code how many decimal digits to consider (to avoid numerics problem and since it is much more than sufficient for our goals, the maximum value allowed is 6).
- modify the log standard output
- correct numerator and denominator in Rational_Approximations instantiations
- adapt the checks in rhmcExecutable.cpp