Base system accessibility wishlist

This includes documenting wherever appropriate accessibility-related changes made to the base system. Documentation-only changes go into Doc instead.

• Speech output support in vt(4): D35754 available for feature testing.
• Daemon to speak vt(4) console: D35776 available for feature testing.
• Provide a VTY screenreader (which one?) in the installer itself, as self-configurable as possible, and that can be started on the initial menu with a simple key or key combination.
• Add a VTY screenreader (POLA says the same one) to the packages available from the installer so the installed OS can be speech-friendly from the first boot.
• Document in the handbook.

• Check the installer text and background colors provide enough contrast (including as shades of grey) and or offer options to change them. See High Contrast Installer (email thread) and contrast testing report.
• Document in the handbook.

• Screenreader support in the loader. (Earlier boot stages are probably unfeasible.)
• Speech recognition instead of a keyboard (that's a very tough one, maybe untractable - accents, spelling variants, ESL speakers, and I'm probably missing some).
• Other color schemes than white-on-blue (installer) or white-on-black (out-of-the-box default for VTYs), both configurable from the installer including for the installed OS.