move all usecases into a single folder

...solution/RR-multi-patch-with-gravity-constant-solution.py

...R-multi-patch-plus-gravity/RR-multi-patch-with-gravity.py

...ds/multi-patch/RR-multi-patch-plus-gravity/plots/Makefile

...cache/Errornorm-exact-solution-over-time-with-gravity.dep

...cache/Errornorm-exact-solution-over-time-with-gravity.png

...ty/plots/Tikzcache/Errornorm-exact-solution-over-time.dep

...ty/plots/Tikzcache/Errornorm-exact-solution-over-time.png

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.00.dep

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.00.png

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.01.dep

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.01.png

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.02.dep

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.02.png

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.03.dep

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.03.png

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.04.dep

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.04.png

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.05.dep

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.05.png

...ty/plots/Tikzcache/RR-2-patch-subsequent_errors_t0.06.dep