Make more improvements to the debugging

[fwitte]

The following improvements should be made:

• Be able to print a nice looking tabular structure of the variables, the equations and the equations with its dependents
• Be able to print out which variables were presolved through which equations
• Be able to print a matrix in a humanly readable format to show
  • the incidence matrix
  • the Jacobian matrix
• Specifically for the Jacobian:
  • Show the values where they are expected and highlight values expected to be non-zero in some kind of color
  • Show nothing (maybe a just a dot) indicating no entry is expected here
• After preprocessing:
  • Let the user analyse the incidence matrix in case too many parameters or too few parameters are specified
  • Show the list of variables not in connection with any of the equations
  • Show the list of equations not depending on any variable