Fix faulty generic parsing and syntax examples

[agjohnson]

This removes improperly chained generic syntax:

.. dn:class:: Foo<T><T><T>

And adds support and test cases for:

.. dn:class:: Foo<T, T>
.. dn:class:: Foo<TFoo, TBar>
.. dn:class:: Foo<T, <T, <string>>>

etc.

Sphinx alias linking is completely overridden, as it interferes with generic syntax

[ericholscher]

:ship: