[gui] Add treemap as subdirectory & fix platform-specific errors

Author: magnustymoteus

gui/CMakeLists.txt

@@ -26,6 +26,8 @@ if(webgui)
    add_subdirectory(browsable)
    add_subdirectory(browserv7)
 
+   add_subdirectory(treemap)
+
    if(root7)
       add_subdirectory(canvaspainter)
       add_subdirectory(fitpanelv7)

gui/treemap/inc/ROOT/RTreeMapPainter.hxx

@@ -54,7 +54,7 @@ public:
 
    struct Node final : public ROOT::Experimental::RTreeMapBase::Node, public TObject {
    public:
-      ClassDef(Node, 1);
+      ClassDefOverride(Node, 1);
    };
    RTreeMapPainter() = default;
    void Paint(Option_t *opt) override;

gui/treemap/src/RTreeMapBase.cxx

@@ -17,7 +17,7 @@
 
 #include <cmath>
 #include <iomanip>
-#include <iostream>
+#include <sstream>
 #include <unordered_map>
 #include <algorithm>