4.0.2 (stable):

Build:
* Meson build: Use relative paths to untracked/
  (Mingli Yu) Merge request !61
* [gdk|gtk]mmconfig.h.*: Don't dllimport on MinGW
  (Chun-wei Fan) Issue #90 (Lukas K.)
* Meson build: Make it possible to use gtkmm as a subproject
  (Kjell Ahlstedt) Merge request !62 (BogDan Vatra)
* Meson build: No implicit_include_directories
  (Kjell Ahlstedt)
* MSVC build: Gtk: Export some classes selectively
  (Chun-wei Fan)