documentation and folded item delegates from old code back in

app/widget/projectexplorer/projectexplorernavigation.cpp

@@ -0,0 +1,15 @@
+#include "projectexplorernavigation.h"
+
+#include <QHBoxLayout>
+
+#include "ui/icons/icons.h"
+
+ProjectExplorerNavigation::ProjectExplorerNavigation(QWidget *parent) :
+  QWidget(parent)
+{
+  QHBoxLayout* layout = new QHBoxLayout(this);
+
+  dir_up_btn_ = new QPushButton(this);
+  dir_up_btn_->setIcon(olive::icon::DirUp);
+  layout->addWidget(dir_up_btn_);
+}