app: merge app/internal/wm into package app

The app and app/internal/wm packages are tightly coupled, requiring
quite a bit of forwarding types, values and constants from the internal
package to export it. Further, no other package imports package wm.

This change merges the two packages.

While here, drop the pre-Go 1.14 SIGPIPE workaround.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/GioActivity.java

@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package org.gioui;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.content.res.Configuration;
+
+public final class GioActivity extends Activity {
+	private GioView view;
+
+	@Override public void onCreate(Bundle state) {
+		super.onCreate(state);
+
+		this.view = new GioView(this);
+
+		setContentView(view);
+	}
+
+	@Override public void onDestroy() {
+		view.destroy();
+		super.onDestroy();
+	}
+
+	@Override public void onStart() {
+		super.onStart();
+		view.start();
+	}
+
+	@Override public void onStop() {
+		view.stop();
+		super.onStop();
+	}
+
+	@Override public void onConfigurationChanged(Configuration c) {
+		super.onConfigurationChanged(c);
+		view.configurationChanged();
+	}
+
+	@Override public void onLowMemory() {
+		super.onLowMemory();
+		GioView.onLowMemory();
+	}
+
+	@Override public void onBackPressed() {
+		if (!view.backPressed())
+			super.onBackPressed();
+	}
+}