restyled preferences dialog

- Frameless dialog super class
Merge branch 'master' of https://github.com/worklist/hifi into 19508
Merge branch 'master' of https://github.com/worklist/hifi into 19508
Merge branch 'master' of https://github.com/worklist/hifi into 19508
UI changes
Merge branch 'master' of https://github.com/worklist/hifi into 19508
Bad merge fix
Merge branch 'master' of https://github.com/worklist/hifi into 19508
styling

bad merge fix
merge upstream
Merge branch 'master' of https://github.com/worklist/hifi into 19508
Merge branch 'master' of https://github.com/worklist/hifi into 19508
Bad merge fixes
merge
Merge branch 'master' of https://github.com/worklist/hifi into 19508
Merge branch 'master' of https://github.com/worklist/hifi into 19508
Merge branch 'master' of https://github.com/worklist/hifi into 19508

Conflicts:
	interface/src/Menu.h
New layout
Merge branch 'master' of https://github.com/worklist/hifi into 19508

Conflicts:
	interface/interface_en.ts
styling QSlider