News in 4.99.0, 2021-02-12
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GtkSourceView 4.99.0 is a beta release targeting GTK 4 and will eventually
become GtkSourceView 5.0.

It is the largest release of GtkSourceView in many releases and contains new
subsystems and performance improvements. More than 300 commits are part of this
release touching everything from syntax highlighting to a new snippet engine.

As GtkSourceView 4.99 moves to using PCRE2, it is possible that some language
definitions will need tweaking for differences between PCRE and PCRE2. So far,
very few changes were necessary within the GtkSourceView codebase but external
language specifications may require some tweaks. In particular, improper
escaping is the only incompatability seen thus far.

* Improvements when converting Pango styling to CSS
* Build system improvements
* GObject modernization
* A new completion engine has been added that reduces overhead and fits with
  GTK 4 lazy lists more closely. It is largely based on the code and design
  from GNOME Builder.
* GtkSourceGutterRenderers are now a GtkWidget allowing more interesting
  features to be implemented by applications.
* Undo management was moved into GTK 4 directly and is no longer part of
  GtkSourceView.
* Syntax highlighting has moved to PCRE2 and utilizes a JIT when available.
* GtkSourceBuffer has a new "cursor-moved" signal.
* A new font "Builder Blocks" from GNOME Builder has been bundled for use
  in the GtkSourceMap.
* To speed up gutter operations, a new GtkSourceLines abstraction has been
  added which allows fewer passes across the source buffer to extract features
  for display.
* A new snippet engine based originally upon GNOME Builder's but with a
  new snippet language based on XML similar to language-specs and
  style-schemes.
* A new "Assistant" abstraction which can be used for tooltips and eventually
  hover providers.
* Updates to go.lang, cmake.lang, meson.lang, csharp.lang.
* Translation updates