Render invisible attribute
Render invisible attribute

Implement invisible mode by setting the foreground color to be the same
as the background color. Not rendering anything would also be an
alternative, but this seems less likely to cause surprises in
conjunction with any hacks.

Signed-off-by: Roberto E. Vargas Caballero <7478dba6682c631c29bb5d8db3571688fdd8aa67@shike2.com>

google/mt,google/mt