Add Python wrapper to ecl and use it to test functionality

* Add SWIG interface definition (and external numpy interface) to ecl classes
* Add section in CMakeLists.txt to build Python bindings and execute
  Python-based tests
* Write (property-based) tests that show the basic functionality of the Python
  bindings and the EKF (using pytest and hypothesis libraries)
* Write minimal benchmark for the EKF update (using benchmark plugin for pytest)
* Add plotting utilities to analyze tests
* Add lint script to keep the Python scripts clean

EKF/tests/pytest/plot_utils.py

@@ -0,0 +1,91 @@
+###############################################################################
+#
+# Copyright (c) 2017 Estimation and Control Library (ECL). All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name ECL nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+###############################################################################
+
+"""Plotting utilities for the Python-based tests
+
+@author: Peter Dürr <Peter.Duerr@sony.com>
+"""
+from __future__ import print_function
+from __future__ import unicode_literals
+from __future__ import division
+from __future__ import absolute_import
+
+import inspect
+from contextlib import contextmanager
+
+try:
+    from matplotlib import pyplot as plt
+    import seaborn as sns
+except ImportError as err:
+    print("Cannot import plotting libraries, "
+          "please install matplotlib and seaborn.")
+    raise err
+
+# Nice plot defaults
+sns.set_style('darkgrid')
+sns.set_palette('colorblind',
+                desat=0.6)
+
+
+def quit_figure_on_key(key, fig=None):
+    """Add handler to figure (defaults to current figure) that closes it
+    on a key press event.
+    """
+    def quit_on_keypress(event):
+        """Quit the figure on key press
+        """
+        if event.key == key:
+            plt.close(event.canvas.figure)
+
+    if fig is None:
+        fig = plt.gcf()
+    fig.canvas.mpl_connect('key_press_event', quit_on_keypress)
+
+
+@contextmanager
+def figure(name=None, params=None, figsize=None, subplots=None):
+    """Setup a figure that can be closed by pressing 'q'
+    """
+    # As a default, use the name of the calling function as the title of the
+    # window
+    if name is None:
+        # Get name of function calling the context from the stack
+        name = inspect.stack()[2][3]
+    fig, axes = plt.subplots(*subplots, figsize=figsize)
+    fig.canvas.set_window_title(name)
+    quit_figure_on_key('q', fig)
+    yield fig, axes
+    if params is not None:
+        name += "\n" + repr(params)
+    axes[0].set_title(name)
+    plt.show(True)