Remove code duplication of timing.c in several manual implementations #58
Description
There is a duplicated timing.c in several of the C and C++ NemoLite2d manual implementations.
An option would be to place the file in the NemoLite2D common folder. But I am not sure which Makefile should compile it, the one in that folder (right now it just deals with Fortran files) or the one from the specific manual version that needs the timer. @arporter Is the common folder the right place for this file? What building solution do you prefer?