ansi: show ANSI art in a UTF-8 terminal, or as plain or shaded text

Draws an .ans file into a grid the way an ANSI-BBS terminal would (cursor
moves, the wrap at the SAUCE width, iCE colours) and writes it out as UTF-8:
in colour, --plain, or --mono with coloured areas shaded by brightness. info
prints the SAUCE record. One C99 file with no dependencies.

.gitignore

@@ -0,0 +1 @@
+ansi