added TestLinearBeamProblem and EnergyErrors for Discretizations and fixed...

Closes #158

See merge request mpp/cardmech!184

Merge remote-tracking branch 'origin/feature' into 158-test-error-measures-for-dirichletbeam-expanded

Resolve "Resolve deprecated warnings"

See merge request mpp/cardmech!183

actual status of monodomain

See merge request mpp/cardmech!181

Resolve "Fix Error in LinearMaterial"

Closes #165

See merge request mpp/cardmech!180

added possibility to use different time integration schemes for ion concentration for exponential integrator

added missing errors

Closes #164

See merge request mpp/cardmech!178

Merge branch '163-improve-initial-deformedvolume-for-eg-and-add-dg-and-eg-to-testvolume' into 'feature'

Resolve "Improve Initial/DeformedVolume for EG and add DG and EG to TestVolume"

Closes #163

See merge request mpp/cardmech!177

Merge remote-tracking branch 'origin/feature' into 163-improve-initial-deformedvolume-for-eg-and-add-dg-and-eg-to-testvolume

Merge branch '156-implement-energyerror-and-rename-old-energyerror-to-strainenergyerror' into 'feature'

Resolve "Implement EnergyError and rename "old" EnergyError to StrainEnergyError"

Closes #156

See merge request mpp/cardmech!176

Merge remote-tracking branch 'origin/feature' into 156-implement-energyerror-and-rename-old-energyerror-to-strainenergyerror