Split P3M::run into run and compute_far.
summation and collection of timings moved to function (usable by ik and ad).
ik FFT estimate fixed.
reinsert ik diff into timing.
Merge branch 'p3m-refactor' of https://github.com/g-sichardt/scafacos into p3m-refactor

Conflicts:
	lib/p3m/src/run.cpp