Merge branch 'thermocapillary' into 'master'

...books/10_tutorial_conservative_allen_cahn_two_phase.ipynb

doc/notebooks/12_Thermocapillary_flows_heated_channel.ipynb

doc/notebooks/13_Thermocapillary_flows_droplet_motion.ipynb

doc/sphinx/tutorials.rst

lbmpy/advanced_streaming/communication.py

lbmpy/boundaries/boundaryconditions.py

lbmpy/boundaries/boundaryhandling.py

lbmpy/creationfunctions.py

lbmpy/forcemodels.py

lbmpy/methods/creationfunctions.py

lbmpy/phasefield_allen_cahn/analytical.py

lbmpy/phasefield_allen_cahn/contact_angle.py

lbmpy/phasefield_allen_cahn/derivatives.py

lbmpy/phasefield_allen_cahn/kernel_equations.py

lbmpy/phasefield_allen_cahn/numerical_solver.py

lbmpy/phasefield_allen_cahn/parameter_calculation.py

lbmpy/phasefield_allen_cahn/phasefield_simplifications.py

lbmpy/stencils.py

lbmpy_tests/phasefield_allen_cahn/test_analytical.py

.../phasefield_allen_cahn/test_phase_field_derivatives.ipynb