new make dependency tracking system in LAMMPS-ICMS

hi everybody,

for those (few?) of you that follow the LAMMPS-ICMS git repository, i
would like to alert you of a change that i am about to push to the
public repository now.

i have implemented for a few machines (including "mpi" and "serial") a
new way to generate and update dependencies for sources, which is
hopefully faster than the current system and less easily confused by
certain packages that require deep changes to global classes. this
scheme uses an adapted version of mkdep.c as it was used a long time
ago in the linux kernel and instead of creating new <name>.d files for
every <name>.cpp file, there is going to be just one .depend file and
since the creation of this file is very fast, it will be recreated
every time.

the changes are designed to be backwards compatible to all custom
makefiles, which will continue to used the old dependency tracking
system. you may see some error messages, but they can be safely
ignored in that case and the build should continue normally.

i would very much appreciate any feedback of those that give it a try.
i am particularly interested in portability issues and performance
comparisons. you can either reply to this e-mail or post an issue on
the github or bitbucket mirrors.

thanks for your attention and thanks in advance for everybody sending feedback.