This doesn't really change any behavior, but adjusts the types
such that CSIs that set colors have the potential to track the
alpha channel and that can make it through to the GUI/render layer.
It's been replaced with an opaque termwiz error type instead.
This is a bit of a more conservative approach than that in (refs: #407)
and has less of an impact on the surrounding code, which appeals to
me from a maintenance perspective.
refs: #406
refs: #407
This restructures the LineEditor to allow the hosting application to
override key presses and apply custom edits to the editor buffer.
Methods for performing predefined actions and for accessing the line
buffer and cursor position have been provided/exposed to support this.
One consequence of this change is that the editor instance needs to be
passed through to the host trait impl and that means that the LineEditor
can no longer be generic over `Terminal`. Instead we now take `&mut dyn
Terminal` which was how the majority of non-example code was using it in
any case. This simplifies a bit of boilerplate in wezterm but adds an
extra line to the most basic examples.
