This command is an atlas loader command, or one that makes use of the atlas loader template to load
atlases from the filesystem. An atlas loader command receives an arbitrary number of input
atlas files on the command line, through the <input-atlases...> argument. A few quick
examples:
#$ example-loader-command myatlas1.atlas myatlas2.atlas --opt=optarg
#$ example-loader-command ~/*.atlas --opt=optarg
#$ example-loader-command atlas1.atlas atlas2.atlas atlas3.atlas --strict
If an atlas loader command cannot find one of the specified atlas files, it will
simply skip over loading the file. This is unless the '--strict' option is applied,
in which case the load will fail fast.

The '--combine' option forces the atlas loader command to process its input atlases as a single MultiAtlas.
The MultiAtlas construction step will occur before the process step, and then the processing will be applied to
the newly combined MultiAtlas. The combined MultiAtlas will always have the name 'combined.atlas'.

The '--parallel' option forces the atlas loader command to process the input atlases in parallel.
