Respect OS reported DPI scale

[WillyJL]

scaling done in 2 parts now:

• user chosen scaling in-app
• dpi scaling reported by glfw

both affect sizing of all elements
fonts are generated using user chosen scaling, then resized using dpi scaling

this should mean that:

• high dpi monitors (like 4k) should work correctly out of the box without user intervention
• content scaling chosen in os display settings is respected and reacted to without restart
• fonts may look a little blurry as they are not generated in the actual resolution theyre drawn at

unfortunately font blurriness is unlikely to be solvable, as opengl has a fixed texture size so generating the fonts at such huge sizes is not possible. this compromise means that everything is atleast sized correctly and working, but will have some slight blurriness when using content scaling

also, this fixes some elements (borders, scroll bar, spacing) not being scaled correctly