These were showing up as unrecognized sequences on my mac, and I
wondered what they were. We now parse them and do nothing with
them, other than print out the parsed form :)
I wanted to see how much work remains to enable iterm2 image
display; one of the blockers was a limit in the size of the
buffer in the vte crate, which has been removed in my fork
of vte.
As part of testing our ability to absorb that data, I found
a couple of issues with applying the image cells to the display,
so this commit also takes care of that.
We still don't have code to connect the cell image data to the
opengl render layer.
The saturating_sub was going to be an attempt at the look-back alluded
to in the TODO comment, but I decided not to implement that in this
iteration.
The effect of this was that double clicking the `m` in a sequence like
` master` would only select the `m` instead of the `master` string.
previously this just used unicode word segmentation rules, but that
is insufficient for most technical users.
Change this to look for sequences that are non-whitespace and not
enclosed by bracket/quote delimiters. This allows selecting file names
with a double click, which was my main issue.
We don't yet have any code to render them, and the vte parser seems
to truncate incoming image sequences ~1kb in size, so more work is
needed to make this useful.
