First Coulomb implementation that works

After fixing all possible divisions by zero I was able to find in the
Coulomb collision I think that this is a first working implementation of
a Coulomb operator based on moments.

Still to test a few things, modify the manual but I would say that I'm
satisfiyed right now. This operator won't be used that often but maybe
improving efficiency is still needed.

In the future a binary operator is required to be able to study cases
out of Maxwellian equilibrium.

src/modules/moduleInject.f90

@@ -97,7 +97,7 @@ MODULE moduleInject
 
       self%id         =  i
       self%vMod       =  v / v_ref
-      self%n        =  n / NORM2(n)
+      self%n          =  n / NORM2(n)
       self%T          =  T / T_ref
       self%species    => species(sp)%obj
       tauInject = tau(self%species%n)