bug fix for perfect_model_obs input.nml options

perfect_model_obs now exits cleanly if the user has not provided input_state_files or output_state_files.
Previously, blank entries (" ") for these namelist items could cause perfect_model_obs to hang.

Repository clean-up and DART registration form

removed obsolete code:

• cam-old
• restart_file_tool
• html boilerplate from pre-readthedocs documentation
• null versions of clamp_mod and vert_convert_mod
• io test harnesses
• jekyll website

removed experimental code:

• pnetcdf (for restart files)
• filter.separate_seq (split obs_seq across cores)

Registration info now on the GitHub README.md

NAG compiler fixes and updates to developer tests

• bug fix for fixsytem for the NAG compiler
• new developer test for mpi one-sided communication
• removed obsolete async 4 developer tests

WRF-Hydro diagnostics

Improved DART diagnostics for WRF-Hydro

Documentation and template update

• External forward operator documentation
• Typo fixes for GitHub templates

bug fixes for obs_seq_to_netcdf and grabbufr.x

Bug fixes:

• Added logic to obs_seq_to_netcdf to keep track of whether a files has been created for an epoch during that run of obs_seq_to_netcdf. Previously if there were multiple obs_sequence files in an epoch, the epoch file was being created afresh for each obs_seq file. Thus, only obs from the last file in the list were present in obs_epoch.nc
• The PGI compiler requires a declaration for the STAT function. This prevents STAT exiting with an error when using long filenames.

bug fix for wrf unique level count.

Uninitialized array for unique levels in the wrf model_mod.f90 could lead to forward operator failures depending on the number of processors used.

bug fix for cam-fv model_interpolate

Fixed bug in cam-fv model_interpolate where the incorrect array slice of quad_vals was being passed to quad_lon_lat_evaluate.

bug fix for cam-fv model_interpolate

Fixed bug in cam-fv model_interpolate where the incorrect array slice of quad_vals was being passed to quad_lon_lat_evaluate.

latest version of local particle filter

Latest version of local particle filter from Jon Potterjoy
New mpi_utilities routine get_global_max