reciprocity/ggrc-core — pull request #1393 by bmomberger-reciprocity (2014-05-29 22:06:14+00:00)
Title: Refactor GGRC startup and main frame creation routines.

Changes in this commit:
* No more RELATIONSHP_TYPES or JoinDescriptor or model_descriptors
* WidgetDescriptor is a class you can instantiate to make widgets, with convenience functions for tree or info views
* Mappings is now a class, that can take mappings from multiple extensions
* Mappings can identify certain Direct/Indirect/Proxy mappings as "canonical" replacing JoinDescriptors
* WidgetList allows extensions to define their own widgets to add. Its implementation is currently hacky but consistent with how Mappings is done.