fixed divide-by-zero for progress bar counter

* reported by meyergaa00: https://sourceforge.net/tracker/index.php?func=detail&aid=3304185&group_id=237831&atid=1104176


git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@1075 bbaffbd6-741e-11dd-a85d-61de82d9cad9

src/pycam/Utils/__init__.py

@@ -240,6 +240,10 @@ def get_external_program_location(key):
 class ProgressCounter(object):
 
     def __init__(self, max_value, update_callback):
+        if max_value <= 0:
+            # prevent divide-by-zero in "get_percent"
+            self.max_value = 100
+        else:
             self.max_value = max_value
         self.current_value = 0
         self.update_callback = update_callback
@@ -256,5 +260,5 @@ class ProgressCounter(object):
             return False
 
     def get_percent(self):
-        return 100.0 * self.current_value / self.max_value
+        return min(100, max(0, 100.0 * self.current_value / self.max_value))