import the matplotlib modules and set the style

    Returns
    -------
    plt: pylab
        imported pylab module
    mpl: matplotlib module
        imported matplotlib module

def setup():
    """import the matplotlib modules and set the style

    Returns
    -------
    plt: pylab
        imported pylab module
    mpl: matplotlib module
        imported matplotlib module

    """
    # Latex support can be activated using an environment variable, otherwise
    # the default settings are:
    # - for windows: off
    # - else: on
    use_latex = False
    if('DD_USE_LATEX' in os.environ):
        if os.environ['DD_USE_LATEX'] == '1':
            use_latex = True
    else:
        if platform.system() == "Windows":
            use_latex = False
        else:
            use_latex = True

    already_loaded = 'matplotlib' in sys.modules

    # just make sure we can access matplotlib as mpl
    import matplotlib as mpl

    if not already_loaded:
        mpl.use('Agg')

    import matplotlib.pyplot as plt

    plt.style.use('seaborn')

    # general settings
    mpl.rcParams['font.size'] = 7.0
    mpl.rcParams['axes.labelsize'] = 7.0
    mpl.rcParams['xtick.labelsize'] = 7.0
    mpl.rcParams['ytick.labelsize'] = 7.0
    mpl.rcParams["lines.linewidth"] = 1.5
    mpl.rcParams["lines.markeredgewidth"] = 3.0
    mpl.rcParams["lines.markersize"] = 3.0
    # mpl.rcParams['font.sans-serif'] = 'Droid Sans'

    # mpl.rcParams['font.family'] = 'Open Sans'
    # mpl.rcParams['font.weight'] = 400
    mpl.rcParams['mathtext.default'] = 'regular'

    # mpl.rcParams['font.family'] = 'Droid Sans'

    if use_latex:
        mpl.rcParams['text.usetex'] = True

        mpl.rc(
            'text.latex',
            preamble=''.join((
                # r'\usepackage{droidsans}',
                # r'\usepackage[T1]{fontenc} ',
                r'\usepackage{sfmath} \renewcommand{\rmfamily}{\sffamily}',
                r'\renewcommand\familydefault{\sfdefault} ',
                # r'\usepackage{mathastext} '
            ))
        )
    else:
        mpl.rcParams['text.usetex'] = False
    import mpl_toolkits.axes_grid1 as axes_grid1
    axes_grid1
    return plt, mpl