First OOP implementation of tagplot.py.

I think it makes more sense to merge oop into dev and not the other way round. Because I changed some namings (files, functions, ...) in oop which are the ones that should be preserved. @m.hock it is sufficient if you approve the MR and I merge it afterwards, if it looks like something's going to break.

tests/test_tagplot.py

 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 '''
-Unittests for TagPlot
+Unittests for tagplot
 '''
 import unittest
 import numpy as np
 import matplotlib.pyplot as plt
-from TagPlot import TagPlot
+from tagplot import tagplot
 
 
 # %% Create data
@@ -36,37 +36,37 @@ plot_engine = "matplotlib"
 method = 1
 
 
-class TestTagPlot(unittest.TestCase):
+class Test_tagplot(unittest.TestCase):
 
     def test_figures(self):
         with self.assertRaises(TypeError):
-            TagPlot('fig', ProjectID, plot_engine, method)
+            tagplot('fig', ProjectID, plot_engine, method)
         with self.assertRaises(TypeError):
-            TagPlot(fig1, plot_engine, prefix=ProjectID)
+            tagplot(fig1, plot_engine, prefix=ProjectID)
 
     def test_prefix(self):
         with self.assertRaises(TypeError):
-            TagPlot(fig, plot_engine, 3, method)
+            tagplot(fig, plot_engine, 3, method)
 
     def test_plotengine(self):
         with self.assertRaises(ValueError):
-            TagPlot(fig, 1, ProjectID, method)
+            tagplot(fig, 1, ProjectID, method)
         with self.assertRaises(ValueError):
-            TagPlot(fig, 'xyz', ProjectID, method)
+            tagplot(fig, 'xyz', ProjectID, method)
 
     def test_idmethod(self):
         with self.assertRaises(TypeError):
-            TagPlot(fig, plot_engine, ProjectID, method='(0,1)')
+            tagplot(fig, plot_engine, ProjectID, method='(0,1)')
         with self.assertRaises(TypeError):
-            TagPlot(fig, plot_engine, ProjectID, method='h')
+            tagplot(fig, plot_engine, ProjectID, method='h')
         with self.assertRaises(TypeError):
-            TagPlot(fig, plot_engine, ProjectID, method='[0,1]')
+            tagplot(fig, plot_engine, ProjectID, method='[0,1]')
 
     def test_location(self):
         with self.assertRaises(TypeError):
-            TagPlot(fig, plot_engine, ProjectID, method, location=1)
+            tagplot(fig, plot_engine, ProjectID, method, location=1)
         with self.assertWarns(Warning):
-            TagPlot(fig, plot_engine, ProjectID, method, location='up')
+            tagplot(fig, plot_engine, ProjectID, method, location='up')
 
 
 if __name__ == '__main__':