Change the dv of rho in spatialDecompose.f90

Change dv from 4*pi*r^2*dr to 4/3*pi*[(i+1)^3-i^3]*dr^3
Fix the possiblity of using uninitialized value in spatialDecompose(_mpi).f90

add initialization of getAtomTypeIndex = -1 to getAtomTypeIndex(i, numAtom)
for avoiding using uninitialized values
(problem found by gfortran -O2 optimization)
Add -O2 optimization in Makefile
Revert "[Untest] Redefine rho and add rho_dv and g to spatialDecompose.f90"

This reverts commit 149576efc6729f248e4d0de37609b68a98f3f069.

Conflicts:

	spatialDecompose/src/spatialDecompose.f90