Small fixes
This MR is a somewhat random, not systematic, collection of code improvements collected in the past. Before running uncrustify, I would like to commit these fixes since otherwise they might get lost.
This MR does:
- spelling fixes
- cleanup unused code and options
- includes cleanup, especially trying to avoid
#include Ippl.h(idea is that a compilation speedup is achieved, and that changes in Ippl don't result in full recompilation. This was partly successful.) - some code improvements