Pan3D command line arguments

By default, invoking pan3d-viewer will launch a tab in your default browser and navigate to localhost:8080. You can change this behavior in a number of ways. For example, you can launch the Pan3D viewer as a local Python server by running

    pan3d-viewer --server

In response, pan3d-viewer will display this message in the terminal:

    App running at:
    - Local:   http://localhost:8080/
    - Network: http://127.0.0.1:8080/

As the message indicates, pointing a browser to http://localhost:8080/ will open the application.

There are other arguments to initialize features and data. Here is the full list:

--help/-h:        Write command info including the list of options to the terminal and exit.
--server:      Launch in server mode, which disables the default behavior of opening a browser tab on startup.
--dataset:     Pass a string with this argument to specify a target dataset. This value can be either a local path or remote URL. This value must be readable by `xarray.open_dataset()`.
--config_path: Pass a string with this argument to specify a startup configuration. This value must be a local path to a JSON file which adheres to the schema specified in the [Configuration Files documentation](../api/configuration.md). A dataset specified in this configuration will override any value passed to `--dataset`.
--catalogs:    Pass one or more strings which reference available catalog modules (options include "pangeo", "esgf"). If specified, the Catalog Search interface will become available in the left sidebar. See the Catalog Search Tutorial for more information.
--debug:       Launch in debug mode, which will include more terminal output. Intended for developer use.