pantheon.gala: 2019-05-31 -> 2019-07-01

Changes: https://github.com/elementary/gala/compare/102481356066...5f1dbf15a75

Fixes:
https://github.com/elementary/gala/issues/444
https://github.com/elementary/gala/issues/561
https://github.com/elementary/gala/issues/13
https://github.com/elementary/gala/issues/487