With changes in setuptools and in how subpackages work in Python, there were some problems with how multiple xstatic pacakages interacted. XStatic 2.0.0 (https://github.com/xstatic-py/xstatic/pull/14) solves those problems, but requires changes in the xstatic packages themselves.

We should repackage all of Horizon's xstatic dependencies and switch to using XStatic 2.0.0.

The changes necessary are detailed at https://github.com/xstatic-py/xstatic/issues/15