Update focuswriter to 1.7.2
- FIXED: Minimum sizes for page counts were too high.
- FIXED: Window icon didn't work in Wayland.
- Require Qt 5.9.
- Improved loading locales.
- Translation updates: Friulian, Korean.
Test Plan: Saved and re-opened a test document, tested themes and formatting
Reviewers: Triage Team, JoshStrobl
Reviewed By: Triage Team, JoshStrobl
Differential Revision: https://dev.getsol.us/D6459