T::E attribute mess

attributes.pl

=for comment

This is messy. According to spec...

  38;1

should yield bold, and it does in urxvt and vte, but not in xterm.

  38;1;3;4;5;7

should yield bold + italic + underline + blink + reverse

which it does in urxvt and vte, but in xterm it yields italic +
underline + blink + reverse

ON THE OTHER HAND

  38:5;1
  38:5;1;2;3;4;5;6

yields attributes correctly in xterm, urxvt and vte.

HOWEVER

  38;5;220

yields yellow text, and

  38;5;220;5

yields yellow, blinking text, but

  38:5;220;5

yields blinking non-colored text.

Ergo, no safe way of adding color and attributes in the same sequence,
so if we want to add bold, italic, underline and color index 220 to
input, we would have to do

  38:5;1;3;7;38;5;220


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