Remove redundant plot.py
## Description

The `plot.py` module is redundant and should be removed. Was renamed to `line.py`, but not properly cleaned up.
diff --git a/pyfar/plot/plot.py b/pyfar/plot/plot.py
deleted file mode 100644
index b7e4b9e3..00000000
--- a/pyfar/plot/plot.py
+++ /dev/null
@@ -1,135 +0,0 @@
-import matplotlib.pyplot as plt
-import numpy as np
-
-from ._interaction import (
-    AxisModifierLinesLinYAxis,
-    AxisModifierLinesLogYAxis)
-from .ticker import (
-    LogFormatterITAToolbox,
-    LogLocatorITAToolbox)
-
-
-def plot_time_dB(signal, log_prefix=20, log_reference=1, **kwargs):
-    """Plot the time signal of a pyfar audio signal object.
-
-    Parameters
-    ----------
-    signal : Signal
-        An audio signal object from the pyfar Signal class
-    **kwargs
-        Keyword arguments that are piped to matplotlib.pyplot.plot
-
-    Returns
-    -------
-    axes :  Axes object or array of Axes objects.
-
-    Examples
-    --------
-    """
-    x_data = signal.times
-    y_data = signal.time.T
-
-    fig, axes = plt.subplots()
-
-    data_dB = log_prefix*np.log10(np.abs(y_data)/log_reference)
-    ymax = np.nanmax(data_dB)
-    ymin = ymax - 90
-    ymax = ymax + 10
-
-    axes.plot(x_data, data_dB, **kwargs)
-
-    axes.set_ylim((ymin, ymax))
-    axes.set_xlabel("Time [s]")
-    axes.set_ylabel("Amplitude [dB]")
-    axes.grid(True)
-
-    modifier = AxisModifierLinesLogYAxis(axes, fig)
-    modifier.connect()
-
-    plt.show()
-
-    return axes
-
-
-def plot_time(signal, **kwargs):
-    """Plot the time signal of a pyfar audio signal object.
-
-    Parameters
-    ----------
-    signal : Signal
-        An audio signal object from the pyfar Signal class
-    **kwargs
-        Keyword arguments that are piped to matplotlib.pyplot.plot
-
-    Returns
-    -------
-    axes :  Axes object or array of Axes objects.
-
-    Examples
-    --------
-    """
-    x_data = signal.times
-    y_data = signal.time.T
-
-    fig, ax = plt.subplots()
-
-    ax.plot(x_data, y_data, **kwargs)
-
-    ax.set_xlabel("Time [s]")
-    ax.set_ylabel("Amplitude")
-    ax.grid(True)
-
-    modifier = AxisModifierLinesLinYAxis(ax, fig)
-    modifier.connect()
-
-    plt.show()
-
-    return ax
-
-
-def plot_freq(signal, log_prefix=20, log_reference=1, **kwargs):
-    """Plot the absolute values of the spectrum on the positive frequency axis.
-
-    Parameters
-    ----------
-    signal : Signal object
-        An adio signal object from the pyfar signal class
-    **kwargs
-        Keyword arguments that are piped to matplotlib.pyplot.plot
-
-    Returns
-    -------
-    axes : Axes object or array of Axes objects.
-
-    Examples
-    --------
-    """
-    fig, axes = plt.subplots()
-
-    eps = np.finfo(float).tiny
-    data_dB = log_prefix*np.log10(np.abs(signal.freq)/log_reference + eps)
-    axes.semilogx(signal.frequencies, data_dB.T, **kwargs)
-
-    axes.set_xlabel("Frequency [Hz]")
-    axes.set_ylabel("Magnitude [dB]")
-
-    axes.set_xscale('log')
-    axes.grid(True, 'both')
-
-    ymax = np.nanmax(data_dB)
-    ymin = ymax - 90
-    ymax = ymax + 10
-
-    axes.set_ylim((ymin, ymax))
-    axes.set_xlim((20, signal.sampling_rate/2))
-
-    modifier = AxisModifierLinesLogYAxis(axes, fig)
-    modifier.connect()
-    axes.xaxis.set_major_locator(
-        LogLocatorITAToolbox())
-    axes.xaxis.set_major_formatter(
-        LogFormatterITAToolbox())
-
-    plt.show()
-
-    return axes
['pyfar/plot/plot.py']