Added OpenMP shared memory parallelism based on changes in threading branch. Works for ifort, but not for gfortran.
Changed all atomics to criticals. gfortran now produce correct k-effective.
Removed matching_bins from TallyObject type and made it threadprivate. Still have race condition with Lists.
Make active tally lists threadprivate.
Added OpenMP threading for fixed source runs.
Enclose global leakage tally in omp critical.
Add OPENMP Makefile variable to installation instructions.
Merge branch 'develop' into threading-new
Make sure thread fission banks are deallocated.
Merge branch 'develop' into threading-new
Change last instance of omp atomic to omp critical.
Merge branch 'develop' into threading-new
Add option to set number of threads in settings.xml and command line.
Merge branch 'develop' into threading-new

Conflicts:
	src/initialize.F90
Change command-line options.
Add OpenMP tests (also fix PEP8 compliance in test_compile.py).
Add description of <threads> element in user's guide.
Mention command-line flags in user's guide.
Update man page with -s, --threads option.
Fixed a typo in addition to <threads> docs entry.