First attempt at Coulomb collisions

First attemp for Coulomb collisions based on the moments distribtuions.
Still the method is not done and far from being complete but input
options and basic math are implemented.

src/fpakc.f90

@@ -74,7 +74,7 @@ PROGRAM fpakc
     tColl = omp_get_wtime()
     !$OMP END SINGLE
 
-    IF (doMCC) THEN
+    IF (doMCCollisions) THEN
       CALL meshForMCC%doCollisions(t)
 
     END IF
@@ -86,7 +86,7 @@ PROGRAM fpakc
     tCoul = omp_get_wTime()
     !$OMP END SINGLE
 
-    IF (ASSOCIATED(mesh%doCoulomb)) THEN
+    IF (doCoulombScattering) THEN
       CALL mesh%doCoulomb()
 
     END IF