Implements tracking bunch back in time; replace queues for time step size, num time steps and zstop with class that stores all these informations in a list; let the SOURCE element absorbe all particles in case of back tracking; disables automatic centering of FROMFILE distributions;

- use std::cout instead of Ippl's Inform class
- fixes for H5hut version 2

Use different chains of random numbers on each core of a parallel run in CollimatorPhysics. Furhtermore fix simulation time after all particles were in material and fix spurious structure in longitudinal position with period length of time step that was present after passage of material.

bugfix: increase population by number of worker groups; arguments as members to avoid multiple getarg calls

extend multi-slit language to support bitmap masks; Binary pbms not parsed correctly yet, working on it

IPPL/FFT cleanup:
- header added to file
- obsolete files removed
- line indentation fixed
- required functions and macros moved from c_utils.{c,h} moved to fftpack.cpp

renaming Collimator to CCollimator where C stands for cyclotron; all other collimators are implemented using FlexibleCollimator; This also fixes #224

first version of multi-slit/pepperpot/what ever aka flexible collimator. However way to slow to be practical

update required cmake version to 3.1 after change in 0e771d47; cleanup: cmake version only required at top level

using affine transformation instead of coordinate transformation. This allows for shear and perspective operations (to be implemented).