Implement About Dialog

Prepared XDG icon theme in :/icons/multimc. will only be usefull as soon
as Qt decides to support custom fallback themes. use the resources
directly for now.

gui/aboutdialog.cpp

@@ -0,0 +1,23 @@
+#include "aboutdialog.h"
+#include "ui_aboutdialog.h"
+
+#include <QIcon>
+#include <QApplication>
+
+AboutDialog::AboutDialog(QWidget *parent) :
+    QDialog(parent),
+    ui(new Ui::AboutDialog)
+{
+    ui->setupUi(this);
+
+    ui->icon->setPixmap(QIcon(":/icons/multimc/scalable/apps/multimc.svg").pixmap(64));
+
+    connect(ui->closeButton, SIGNAL(clicked()), SLOT(close()));
+
+    QApplication::instance()->connect(ui->aboutQt, SIGNAL(clicked()), SLOT(aboutQt()));
+}
+
+AboutDialog::~AboutDialog()
+{
+    delete ui;
+}