GH-338, GH-513, GH-700 Unify edit instance with console window

* The resulting instance window can be closed at any point.
* Main window is kept open and running instances are marked with a badge.
* Multiple instances can now run from the same MultiMC - it's even more **multi** now.
* MultiMC can be entirely closed, keeping Minecraft(s) running.

application/widgets/PageContainer.cpp

@@ -60,7 +60,6 @@ PageContainer::PageContainer(BasePageProviderPtr pageProvider, QString defaultId
 	createUI();
 	m_model = new PageModel(this);
 	m_proxyModel = new PageEntryFilterModel(this);
-	int firstIndex = -1;
 	int counter = 0;
 	auto pages = pageProvider->getPages();
 	for (auto page : pages)
@@ -69,10 +68,6 @@ PageContainer::PageContainer(BasePageProviderPtr pageProvider, QString defaultId
 		page->listIndex = counter;
 		page->setParentContainer(this);
 		counter++;
-		if (firstIndex == -1)
-		{
-			firstIndex = page->stackIndex;
-		}
 	}
 	m_model->setPages(pages);
 
@@ -111,6 +106,23 @@ bool PageContainer::selectPage(QString pageId)
 	return false;
 }
 
+void PageContainer::refresh()
+{
+	m_proxyModel->invalidate();
+	if(!m_currentPage->shouldDisplay())
+	{
+		auto index = m_proxyModel->index(0, 0);
+		if(index.isValid())
+		{
+			m_pageList->setCurrentIndex(index);
+		}
+		else
+		{
+			// FIXME: unhandled corner case: what to do when there's no page to select?
+		}
+	}
+}
+
 void PageContainer::createUI()
 {
 	m_pageStack = new QStackedLayout;

application/widgets/PageContainer.h

@@ -45,6 +45,8 @@ public:
 
 	virtual bool selectPage(QString pageId) override;
 
+	void refresh();
+
 private:
 	void createUI();
 private