Add support for subclassing gio::Application

Cargo.toml

@@ -34,6 +34,7 @@ dox = ["gio-sys/dox", "glib/dox"]
 purge-lgpl-docs = ["gtk-rs-lgpl-docs"]
 embed-lgpl-docs = ["gtk-rs-lgpl-docs"]
 futures = ["futures-preview", "glib/futures"]
+subclassing = ["glib/subclassing"]
 
 [build-dependencies.gtk-rs-lgpl-docs]
 version = "0.1.3"

Gir.toml

@@ -200,6 +200,7 @@ status = "generate"
 [[object]]
 name = "Gio.Application"
 status = "generate"
+subclassing = true
 manual_traits = ["ApplicationExtManual"]
     [[object.signal]]
     name = "open"

src/lib.rs

@@ -73,3 +73,7 @@ mod auto;
 mod gio_future;
 #[cfg(feature = "futures")]
 pub use gio_future::*;
+
+#[macro_use]
+#[cfg(feature = "subclassing")]
+pub mod subclass;