This adds support for the `hidden` escape sequence `\e[8m`, which will
render the text as invisible.
This has also raised a few questions about the rendering of foreground
and background colors and their interaction with the different escape
sequences. Previously, Alacritty has oriented itself after URxvt, which
has some strange and unexpected behavior.
The new implementation of color inversion is modeled after XTerm, which
has a consistent pattern of always inverting the foreground and
background colors. This should hopefully lead to less confusion for the
user and a more consistent behavior.
A full matrix showcasing the new way Alacritty inverses text can be
found here:
https://i.imgur.com/d1XavG7.png
This fixes#1454 and fixes#1455.
d387ebe1d7
