Fix/minor improvements

@osander: Can you have a look? This MR will:

• Add timer to print the overall time and the time used for one trustregion step
• Clean up mooneyrivlinenergy: Only take values that are actually used from the parset-file
• Add try{}catch{} around the energy calculation and the solve() call inside the trustregion solver
• Throw an exception in Mooneyrivlindensity if det(F) < 0