This was an off-by-one issue when using scroll margins just shorter
than the screen and when scrollback is enabled.
Added a unit test to verify the behavior.
I've had mixed results with esctest; the IRM and cursor save/restore
tests fail for me in terminal.app, iterm2 and xterm, and fail in the
same way on wezterm, so I'm not sure if I'm not running those tests
correctly. However, they did encourage the discovery of some other
real issues in the wezterm emulation.
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.
Reduces the size of the full screen serialized size from 40k -> 13k.
Note that the `zlo` crate (which doesn't appear to have a repo
on github any longer; sources are only found in the crates.io
documentation source view), employes zigzag encoding of all integers
and floating point values and takes the size down to just under 10k.
A todo is to follow up on that and see if we could adopt the same
scheme in varbincode.
The `directories` crate unconditionally and eagerly tries to spawn
`xdg-user-dir` for all possible directories that it might be asked
about. This is relatively expensive and undesirable.
Shift to the `dirs` crate instead, which doesn't seem to need
to run `xdg-user-dir` at all.
Maintain these probed dirs as singletons via lazy_static.
