The language server keeps track of the content of currently edited
files by receiving updates about edit actions.
Also, C++ autocompletion is no longer tied to HackStudio itself and
moved to be part of the language server.
This patch adds an optional mode where TextEditor highlights trailing
whitespace characters on each line with a nice reddish dither pattern.
We should probably make this themable and I'm sure it could be nicer
somehow, but this is just a first cut and I do kinda like it. :^)
TextDocument::first_word_break_before was refactored out to be able
to be used in multiple places throughout the project. It turns out
that its behaviour needs to be slightly different depending on
where its called, so it now has a start_at_column_before flag
to decide which letter it "thinks" was clicked.
Oops, we can't be appending substrings of a string we just deleted!
Fix this by building up the new line instead of trying to clear and
append in place. This works out nicely as we now do fewer document view
updates when removing a range. :^)
A TextDocumentLine is now backed by a non-null-terminated sequence of
Unicode codepoints encoded as UTF-32 (one u32 per codepoint.)
This makes it possible to view and edit arbitrary Unicode text without
strange cursor and selection behavior. You can freely copy and paste
emojis between TextEditor and Terminal now. :^)
Storing UTF-32 is quite space-inefficient, but we should be able to
use the same optimization techniques as LibVT does to reduce it in
the typical case where most text is ASCII.
There are a lot of things that can be cleaned up around this code,
but this works well enough that I'm pretty happy with it.
