Initial GUI support for output module settings

Introduces OutputModuleConfigurationWidget; note that this has to be
set on each OutputModule, should have the ability to inherit from
parent classes...  Same widget works for all output modules.  Only
added to vtkRendererOutput right now.

vistrails/core/modules/output_modules.py

@@ -6,7 +6,7 @@
 
 from vistrails.core.configuration import ConfigurationObject, ConfigField, ConfigPath, ConfigURL, get_vistrails_persistent_configuration, get_vistrails_temp_configuration
 from vistrails.core.modules.vistrails_module import Module, NotCacheable, ModuleError
-from vistrails.core.modules.config import IPort, OPort
+from vistrails.core.modules.config import IPort, OPort, ModuleSettings
 import vistrails.core.system
 
 class OutputMode(object):
@@ -66,6 +66,23 @@ def get_field(cls, k):
                 cls_list.extend(c.__bases__)
         return None
 
+    @classmethod
+    def get_all_fields(cls):
+        field_dicts = []
+        cls_list = [cls]
+        while len(cls_list) > 0:
+            c = cls_list.pop(0)
+            if issubclass(c, OutputModeConfig):
+                c.ensure_field_dict()
+                field_dicts.append(c._field_dict)
+                cls_list.extend(c.__bases__)
+        field_dict = {}
+        for fd in reversed(field_dicts):
+            field_dict.update(fd)
+        fields = field_dict.values()
+        fields.sort()
+        return fields
+
     @classmethod
     def get_default(cls, k):
         f = cls.get_field(k)
@@ -145,6 +162,7 @@ class OutputModule(NotCacheable, Module):
     _input_ports = [IPort('value', "Variant"),
                     IPort('mode_type', "String"),
                     IPort('configuration', "Dictionary")]
+    _settings = ModuleSettings(configure_widget="vistrails.gui.modules.output_configuration:OutputModuleConfigurationWidget")
 
     # configuration is a dictionary of dictionaries where root-level
     # keys are mode_types and the inner dictionaries are
@@ -208,6 +226,7 @@ def get_sorted_mode_list(cls):
 
         mode_dict = {}
         for c in reversed(cls_list):
+            c.ensure_mode_dict()
             mode_dict.update(c._output_modes_dict)
         mode_list = [c for c, _ in reversed(sorted(mode_dict.itervalues(), 
                                                    key=lambda x: x[1]))]