This patch includes the actual implementation of Link, which is
implemented as an extension named LinkBaseExtension in App namespace,
and a full view provider ViewProviderLink in Gui. The reason of not
using ViewProviderExtension is because it need full control when
display, not just extending existing functionalities.
Please see [here](https://git.io/fjPue) for more details of the
implementation.
This patch also includes a set of link manipulation commands, and a
task panel for overriding geometry element colors.
Several typos and uniformity fixes.
Note:
*SCL/SimpleDataTypes.py is a upstream stepcode file whose fiz has been submitted upstream and accepted.
*the header of Tools/generateBase/generateMetaModel_Module.xsd had redundant data. It has been removed. Please double check it.
