Loads the package configurations from the global `acorn.cfg` file.

def _load_package_config(reload_=False):
    """Loads the package configurations from the global `acorn.cfg` file.
    """
    global _packages
    from acorn.config import settings
    packset = settings("acorn", reload_)
    if packset.has_section("acorn.packages"):
        for package, value in packset.items("acorn.packages"):
            _packages[package] = value.strip() == "1"