FIX: Use openpyxl instead of xlrd

Fixes #29 (closed)

Summary

Removes the dependency on the discontinued xlrd<=1.2, uses xlrd>=2.0 for xls files and openpyxl for xlsx files.

Focus

Apparently we waited long enough so that Pandas fixed their engines for reading xls(x) files when both xlrd and openpyxl are installed. So only added a unittest for xls files and removed the version limitation

Test Environment

Simply do the unittests and the integrationtests with the updated xlrd version.

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unittests/test_table_importer.py

@@ -77,7 +77,8 @@ class ConverterTest(unittest.TestCase):
         # TODO datatypes are different; fix it
         assert df.d.iloc[0] == datetime.datetime(1980, 12, 31, 13, 24, 23)
 
-    def test_date(self):
+    def test_date_xlsx(self):
+        """Test with .xlsx in order to check openpyxl engine."""
         test_file = os.path.join(os.path.dirname(__file__), "date.xlsx")
         self.importer = XLSImporter(converters={'a': date_converter,
                                                 'b': date_converter,
@@ -91,6 +92,21 @@ class ConverterTest(unittest.TestCase):
         assert df.shape[0] == 2
         assert df.a.iloc[0] == df.b.iloc[0] == df.c.iloc[0]
 
+    def test_date_xls(self):
+        """Test with .xlsx in order to check xlrd engine."""
+        test_file = os.path.join(os.path.dirname(__file__), "date.xls")
+        self.importer = XLSImporter(converters={'a': date_converter,
+                                                'b': date_converter,
+                                                'c': partial(date_converter,
+                                                             fmt="%d.%m.%y")
+                                                }, obligatory_columns=['a'])
+
+        xls_file = pd.io.excel.ExcelFile(test_file)
+        df = xls_file.parse()
+        df = self.importer.read_xls(test_file)
+        assert df.shape[0] == 2
+        assert df.a.iloc[0] == df.b.iloc[0] == df.c.iloc[0]
+
     def test_inc_date(self):
         incomplete_date_converter("2020", fmts={"%Y": "%Y"}) == "2020"
         incomplete_date_converter("02/2020",