Please ignore any commits in this MR prior to
goocanvasenumtypes.h.template: Mark symbols for export, since the items before that commit are covered by the commits in
goocanvas-3.0-meson, as well as the commits in MR !13, which lay the foundations to this MR.
This updates the Meson build files as well as the
goocanvasenumtypes.h.template so that building with Visual Studio is supported out of the box, complete with introspection support.
With blessings, thank you!