Add test to make sure all emitted symbols use fully qualified paths

tests/check_symbols.rs

@@ -0,0 +1,33 @@
+#![no_implicit_prelude]
+#![allow(dead_code)]
+
+extern crate confique;
+extern crate std;
+
+use confique::Config;
+
+
+#[derive(Debug, Config)]
+/// A sample configuration for our app.
+struct Conf {
+    #[config(nested)]
+    http: Http,
+
+    title: std::string::String,
+}
+
+/// Configuring the HTTP server of our app.
+#[derive(Debug, Config)]
+struct Http {
+    /// The port the server will listen on.
+    #[config(env = "PORT")]
+    port: u16,
+
+    /// The bind address of the server. Can be set to `0.0.0.0` for example, to
+    /// allow other users of the network to access the server.
+    #[config(default = "127.0.0.1")]
+    bind: std::net::IpAddr,
+}
+
+#[test]
+fn compiles() {}