Mixeddimension framework

• Implements all common classes and the embedded type of problem.
• Tests a 1d3d embedded 1p-1p problem and a 1p-richards problem
• Important: Now the currentSolutionVector in the model gets deflected by the localjacobian during assembly and resetted after derivative computation this enables all methods computing residuals to use currentSolutionVector entries of random elements and be sure it's always the right value. This makes implemented coupled problem on two grids a lot easier.