DynamicMatrix is essentially a vector of vectors, so the memory layout is
not contiguous. We would like to be able to use algorithms from lapack and
blas, so I changed the backend to be a single std::vector plus index arithmetic

also fix bindings.cc location

# Conflicts:
#	dune/xt/la/eigen-solver/eigen.hh

- copying the options takes up a majority of the computation time for small
matrices. Thus, the copy is avoided by adding a new constructor that stores
a pointer to the options. The old constructors still work and still store
the provided options.
- Also adds a simple options switch to disable all checks