Retrieve additional options for VarScan from the configuration.

def _varscan_options_from_config(config):
    """Retrieve additional options for VarScan from the configuration.
    """
    opts = ["--min-coverage 5", "--p-value 0.98", "--strand-filter 1"]
    resources = config_utils.get_resources("varscan", config)
    if resources.get("options"):
        opts += [str(x) for x in resources["options"]]
    return opts