make the within block estimation different

[lambday]

make the MMD class a template

template <class Derived>
class CMMD
{
  using est_method = typename Derived::est_method; 
  // within block direct for B-test, Linear time test
  // but it is something else for child
};

class CQuadraticTimeMMD :: public CMMD<CQuadraticTimeMMD>
{
};

class CBTestMMD :: public CMMD<CBTestMMD >
{
};

class CLinearTimeMMD :: public CMMD<CLinearTimeMMD >
{
};

[lambday]

can take care of different normalization constant for the tests in the subclasses itself, and the base class can use that to compute variance

[lambday]

done.