added basic last run crash dialog

src/widgets/lastruncrashdialog.cpp

@@ -0,0 +1,18 @@
+#include "lastruncrashdialog.hpp"
+
+#include <QVBoxLayout>
+
+namespace chatterino {
+namespace widgets {
+
+LastRunCrashDialog::LastRunCrashDialog()
+{
+    QVBoxLayout *layout = new QVBoxLayout(this);
+    layout->addWidget(
+        new QLabel("The application wasn't terminated properly last time it was executed."));
+
+    this->setLayout(layout);
+}
+
+}  // namespace widgets
+}  // namespace chatterino