As part of this, the CodeDocument now keeps track of the kind of
difference for each line. Previously, we iterated every hunk every time
the editor was painted, but now we do that once whenever the diff
changes, and then save the type of difference for each line.
The one behavior difference here is that the statusbar used to display
"Unknown" for unknown file types, and "Markdown" for md, but we now
display "Plain Text" for all file types without syntax highlighters.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
