add umlauts handling for paths 2 openscad (fix fails for filenames

containing äöüÄÖÜß)

extensions/fablabchemnitz/paths_to_openscad/paths_to_openscad.py

@@ -412,6 +412,32 @@ def msg_extrude_by_hull_and_paths(id, prefix):
     return msg
 
 
+def remove_umlaut(string):
+    """
+    Removes umlauts from strings and replaces them with the letter+e convention
+    :param string: string to remove umlauts from
+    :return: unumlauted string
+    """
+    u = 'ü'.encode()
+    U = 'Ü'.encode()
+    a = 'ä'.encode()
+    A = 'Ä'.encode()
+    o = 'ö'.encode()
+    O = 'Ö'.encode()
+    ss = 'ß'.encode()
+
+    string = string.encode()
+    string = string.replace(u, b'ue')
+    string = string.replace(U, b'Ue')
+    string = string.replace(a, b'ae')
+    string = string.replace(A, b'Ae')
+    string = string.replace(o, b'oe')
+    string = string.replace(O, b'Oe')
+    string = string.replace(ss, b'ss')
+
+    string = string.decode('utf-8')
+    return string
+
 class PathsToOpenSCAD(inkex.EffectExtension):
 
     def add_arguments(self, pars):
@@ -1319,6 +1345,7 @@ module chamfer_sphere(rad=chamfer, res=chamfer_fn)
             # Remove all punctuation except underscore.
             badchars = string.punctuation.replace("_", "") + " "
             name = re.sub("[" + badchars + "]", "_", name)
+            name = remove_umlaut(name)
 
             self.outfile.write("\nmodule %s(h)\n{\n" % name)
             mi = ""