Improve Medley visibility on modern displays (fonts, cursor, pixel doubling)

[masinter]

I've been trying to improve visibillity in my init by running FONTSET(BIGGER) and (VIDEOCOLOR T).

• The "BIgger" Fonts are missing a backquote.
• The mouse pointer / cursor gets hidden in an all-black window

[Anzus]

There's a LispUsers package XORCURSORPATCH, but the notes say it only works on the Dove.

[nbriggs]

When I made (VIDEOCOLOR T) work for X displays (it didn't previously) I looked at making the cursor reverse as well -- it didn't work in the way that I expected it to (that is, even using an X graphic context that should have made it invert, it didn't). Then I checked against a D-machine version -- it doesn't invert the cursor for (VIDEOCOLOR T) either, so I left it alone. Since the failed attempt at inverting the cursor was dead code it has been removed.

[masinter]

XORing the cursor isn't as promising as other options.
Interlisp/maiko#16
or just setting the cursor color
or doing the cursor in Lisp again?