separate tcl tests into smaller chunks

implement collection of tcl command tests

tests/tclCommands/test_TclCommandAddPolygon.py

@@ -0,0 +1,18 @@
+from FlatCAMObj import FlatCAMGeometry
+
+
+def test_add_polygon(self):
+    """
+    Test add polygon into geometry
+    :param self:
+    :return:
+    """
+
+    self.fc.exec_command_test('new_geometry "%s"' % self.geometry_name)
+    geometry_obj = self.fc.collection.get_by_name(self.geometry_name)
+    self.assertTrue(isinstance(geometry_obj, FlatCAMGeometry), "Expected FlatCAMGeometry, instead, %s is %s"
+                    % (self.geometry_name, type(geometry_obj)))
+
+    points = '0 0 20 0 10 10 0 10'
+
+    self.fc.exec_command_test('add_polygon "%s" %s' % (self.geometry_name, points))