Merged requested to merge disc_patch_revived into master
Implements the changes discussed in #311 (closed).
- The disc patch example is now 400x400x800 in length with correct internal energy.
- The accelerations get truncated at |z-z_disc| > 300 with a cosine transition
- The accelerations are 0 at |z-z_disc| > 380.
- The calculation is significantly faster thanks to the extraction of constant terms.