instead of string.char(0-27), use "/" as an escape followed by
"[0-9][A-R][a-r]", all inside the string.
e.g. digiline_send("chan", "/0this /1is /2some /3colorful /4text")
"/" followed by any other character than the above will be treated as an
invalid color code and will be taken literally.
"//" will print a single slash.
Note: on receipt, all instances of "//" in a message are actually
translated to string.char(30) -- one for each pair. This makes the
scrolling code easier. Keep this in mind if you use the "getstr" and
"getindex" commands.
Also, this expands the max string length to 6 kB, to allow a full 80x25
display with one color code er character. "clear" and "allon" remain at
2kB since that's still enough.
also make sure to `return false` from the scroll_text function if the
scroll timer was last set to a value below the allowed minimum (which
would mean the user/program intended to shut it off by setting it to 0,
or the stepper was called manually, implying no timer)
translate them to bare ISO-8859-1 at print time
Only alters chars with codes > 0x9f, so graphics/symbols in the
0x7f-0x9f range and color and control codes < 0x20 are preserved
The routine assumes that any char code > 0x9f is the first byte of a
two-byte UTF-8 symbol.
Note that due to Minetest's busted formspecs, it's not possible to
actually type-in or copy-paste proper UTF strings to take advantage of
this mode, so it's only useful if the strings are generated by or
imported in from something else (e.g. a URL or something, or a LuaC
program that generates strings)
