Fixes #15

All the MPI code should now be protected with the HAVE_MPI macro
defined at configure time in the config.h file. This commit allows
to make a simple package, recommended to generate a distributable.
See #9

There is also a much more powerful set of autoconf macros to detect
installations of external programs. See #2

Fixes #6

Fixes #4

   - src/dlb                  -> src/LB_core
   - src/dlb/dlb.c            -> src/LB_core/DLB_kernel.c
   - src/utils/dlb_info.c     -> src/utils/dlb.c

This is a test commit

This commit fixes #13

Testing hooks

See #13

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 -v, --version