[qcrmarcc] Always zoom under mouse cursor

Create a window manager or graphics subsystem that always magnifies the screen under the mouse cursor, like a loupe.  Ideally continuously distort (demagnify) the region outside the magnified area so that no area ever disappears or is obscured.

Inspired by text editors (especially for computer programming) where it is difficult to put the cursor precisely between narrow letters like li1|.

Games do this.

We also need to manage mouse acceleration to permit fine movement within the magnified area.