gnome-builder 3.28.2 release.

Changes since last release:

• A leak of buffers when using semantic highlighting as been fixed, which has the potential to significantly reduce memory usage for some languages such as C.
• Various fixes with DTD validation.
• Various correctness fixes in API usage.
• The new task and threading engine has been backported which provides a new layer of saftey for our threading usage.
• Various fixes for the flatpak plugin.
• Ctags tries to be more careful to avoid recursive mining and no longer attempts to load ~/.tags.
• The clang plugin tries harder to cook cflags delivered to libclang.
• A preferences menu item was added back to the perspective selector. It still uses a dialog for preferences.
• The recent-projects plugin performs additional checks to avoid recursive directory cleanup when that would result in deleting some external data.
• A number of miscellaneous memory leaks have been plugged.
• When meson/ninja are not found, a message is displayed to the user in the messages pane.
• The clang plugin will try to drop state as soon as possible to help keep memory usage down.
• The npm modules now marks "node_modules" as an ignored pattern.