Searches experiment and mkexp path for relative file names

Currently for lists only

* set build subdir default to empty (was 'build')
* add option to ignore errors when executing the script (allows missing files)
* add help option
* add option to set build directory explicitly (eg for mtime)
* add support for scripts in current directory
* make support for non-ksh here documents more robust (checks for actual shell)

Fixes long run times for extended jobs/namelist groups

compconfig.py and diffconfig.py were renamed to compconfig and diffconfig

* added debug option to keep temp files (-x)
* added cpu option to set alleged # of cpus per node (-c), set default to 256
* changed namelist handling for new style scripts for levante/bash
* added initial/final date handling for new style scripts

The global/filter/test decorators were re-named, the old names are deprecated