user friendly reporting of config errors

Config errors are collected first, and raised after processing
all modules. This is more user friendly.

+ remove redundant check for predefined accessibles in modules.py
+ fixed error handling for exporting parameters in params.py
+ fixed handling of bare attributes overwriting properties

Change-Id: I894bda291ab85ccec3d771c4903393c808af0a2a

secop/properties.py

@@ -158,7 +158,7 @@ class HasProperties(HasDescriptors):
         cls.propertyDict = properties
         # treat overriding properties with bare values
         for pn, po in properties.items():
-            value = cls.__dict__.get(pn, po)
+            value = getattr(cls, pn, po)
             if not isinstance(value, Property):  # attribute is a bare value
                 po = Property(**po.__dict__)
                 try:
@@ -177,11 +177,11 @@ class HasProperties(HasDescriptors):
         """validates properties and checks for min... <= max..."""
         for pn, po in self.propertyDict.items():
             if po.mandatory:
-                if pn not in self.propertyDict:
+                try:
+                    self.propertyValues[pn] = po.datatype(self.propertyValues[pn])
+                except (KeyError, BadValueError) as e:
                     name = getattr(self, 'name', self.__class__.__name__)
-                    raise ConfigError('Property %r of %s needs a value of type %r!' % (pn, name, po.datatype))
-                # apply validator (which may complain further)
-                self.propertyValues[pn] = po.datatype(self.propertyValues[pn])
+                    raise ConfigError('%s.%s needs a value of type %r!' % (name, pn, po.datatype))
         for pn, po in self.propertyDict.items():
             if pn.startswith('min'):
                 maxname = 'max' + pn[3:]