update , bug fix on Poynting vector definition

v0.1/Formelsammlung.tex

v0.1/Graphiken/drawing_capacity_dielectric.svg

...drawing_capacity_dielectric.svg.2020_11_20_12_42_26.0.svg

v0.1/Graphiken/drawing_capacity_liquid.svg

v0.1/Graphiken/drawing_exercise.svg

v0.1/Graphiken/drawing_filter.svg

v0.1/Graphiken/drawing_massspectro.png

v0.1/Graphiken/drawing_massspectro.svg

v0.1/Graphiken/plattenkondensator.svg

v0.1/elektrostatik.tex

v0.1/em_waves.tex

v0.1/scripts/plot_dipole_fieldlines_pot.py

v0.1/scripts/plot_example.py

v0.1/skript.pdf