Don't crash on duplicates in config

Use last definition of an option instead. Section duplicates are also
supported from now.

Example:

'''
[column_keymap]
a = foo
a = bar

[column_keymap]
b = foobar
'''

is equivalent of:

'''
[column_keymap]
a = bar
b = foobar
'''

test/data/ConfigTest7.conf

+[column_keymap]
+k = foo
+k = bar
+
+[column_keymap]
+z = foobar

test/test_config.py

@@ -165,5 +165,12 @@ class ConfigTest(TopydoTest):
         self.assertNotIn('<Esc', keystates)
         self.assertIn('<Esc>', keystates)
 
+    def test_config28(self):
+        """ test duplicates. """
+        keymap, keystates = config("test/data/ConfigTest7.conf").column_keymap()
+
+        self.assertEqual(keymap['k'], 'bar')
+        self.assertEqual(keymap['z'], 'foobar')
+
 if __name__ == '__main__':
     unittest.main()

topydo/lib/Config.py

@@ -162,7 +162,7 @@ class _Config:
 
         self.config = {}
 
-        self.cp = configparser.RawConfigParser()
+        self.cp = configparser.RawConfigParser(strict=False)
         # allow uppercase config keys
         self.cp.optionxform = lambda option: option
 

topydo/ui/columns/ColumnLayout.py

@@ -49,7 +49,7 @@ def columns(p_alt_layout_path=None):
             'show_all': '0',
     }
 
-    cp = RawConfigParser(defaults)
+    cp = RawConfigParser(defaults, strict=False)
     files = [
         "topydo_columns.ini",
         "topydo_columns.conf",