Overview of Changes in 2.2.0 (since 1.9.0)
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* Add a .pc file [Seth Nickell]
* Various crash fixes [Luca Barbato, Hongli Lai, 
  Shivaram Upadhyayula, Peter Zelezny)
* Build fixes [Havoc Pennington]
* Metal theme drawing improvements [Owen Taylor]
* Improve installation docs [Owen, Piotr Sawuk]
