First functions to compute the eigenvalues of the overlap operator

The fastest way is to use computeAnalyticalEigenvalue_fromIndex(l0,l2,l3,l4) instead of the naive computation that takes the
momenta as input. Also tehre is a function
computeAnalyticalEigenvalue_fromIndex_pAndVarP(int l0, int l1, int l2, int l3, std::complex< double > &nuOfP, std::complex< double > &nuOfVarP)
that simultaniously computes nu(p) and nu(p+(pi,pi,pi,pi)) to reduce some overhead
Added a function to compute the gradient. Also spliutted up the file and added the source fo a file to test the gradient
added a function to compute simultansously the function and the gradient.

However, it is a naive computation. Improvements will follow, once th program is working
Minimization is working now.

Also improved the computation of the fermionic coontribution to use the symmetries of the lattice for an L^3 x L_t
lattice. The modulus of the eigenvalues will be stored to improve the speed.

This improvement will now be implemented in the computation of the gradient and the simultanious computation of the gradient and the function.
Added functions to improve the speed of the computation of the gradient and/or the function
So far finished the class constrainedEffectivePotential

Further changes will come during coding...
Wrote the program that is able to scan the CEP in lambda, yukawa coupling and kappa for the minimium.

However, there is almost no volume dependence, which is reasonable, since the main dependence on the volume comes from the bosonic loop, which is neglected so far.
added the possibility to include the bosonic loop. Does not work properly so far