Merge Ionization into Dev to see changes

The code is compiling but once I try to run it, I am receiving a SegFault without much other comment. 
That happens when I use CUDA 5.5 or 6.0. If I use 6.5 it tells me that it cannot find a CUDA capable device.
Well, in fact it would not be correct if one called getCharge on an already multiply ionized ion. As you remove electrons from the ion and thus put more negative charges into the simulation, the ion's charge has to grow by the same amount. 

The point was that I wanted to have it compile but to do it correctly I either need to access the charge state attribute of the particle first or I need a trait "getChargeState".