Refactor|World|Blockmap: Blockmap now encapsulates Gridmap

The level at which Gridmap was abstracted from Blockmap is not useful.
There are however two meaningful abstractions; 1) Quadtree extraction
with floating-point space region/point lookup, and 2) external storage
allocator and accessor to the data within the Blockmap.

doomsday/client/client.pro

@@ -259,7 +259,6 @@ DENG_HEADERS += \
     include/gl/svg.h \
     include/gl/sys_opengl.h \
     include/gl/texturecontent.h \
-    include/gridmap.h \
     include/hedge.h \
     include/ihplane.h \
     include/library.h \
@@ -612,7 +611,6 @@ SOURCES += \
     src/gl/gl_texmanager.cpp \
     src/gl/svg.cpp \
     src/gl/sys_opengl.cpp \
-    src/gridmap.cpp \
     src/hedge.cpp \
     src/library.cpp \
     src/m_decomp64.cpp \

doomsday/client/include/de_misc.h

@@ -27,7 +27,6 @@
 #include "m_misc.h"
 #include "m_nodepile.h"
 #include "m_profiler.h"
-#include "gridmap.h"
 #include "m_decomp64.h"
 #include <de/stack.h>
 #include <de/mathutil.h>

doomsday/client/include/world/blockmap.h

@@ -25,7 +25,13 @@
 
 #include <de/Vector>
 
-#include "gridmap.h"
+#ifdef min
+#   undef min
+#endif
+
+#ifdef max
+#   undef max
+#endif
 
 namespace de {
 
@@ -35,8 +41,19 @@ namespace de {
 class Blockmap
 {
 public:
-    typedef GridmapCell Cell;
-    typedef GridmapCellBlock CellBlock;
+    typedef Vector2ui Cell;
+
+    /**
+     * POD structure representing a rectangular range of cells.
+     */
+    struct CellBlock
+    {
+        Cell min;
+        Cell max;
+
+        CellBlock(Cell const &min = Cell(), Cell const &max = Cell()) : min(min), max(max) {}
+        CellBlock(CellBlock const &other) : min(other.min), max(other.max) {}
+    };
 
 public:
     /**
@@ -136,10 +153,18 @@ class Blockmap
     int iterate(CellBlock const &cellBlock, int (*callback) (void *elem, void *context), void *context = 0) const;
 
     /**
-     * Retrieve an immutable pointer to the underlying Gridmap instance
-     * (primarily intended for debug purposes).
+     * Render a visual for this gridmap to assist in debugging (etc...).
+     *
+     * This visualizer assumes that the caller has already configured the GL
+     * render state (projection matrices, scale, etc...) as desired prior to
+     * calling. This function guarantees to restore the previous GL state if
+     * any changes are made to it.
+     *
+     * @note Internally this visual uses fixed unit dimensions [1x1] for cells,
+     * therefore the caller should scale the appropriate matrix to scale this
+     * visual as desired.
      */
-    Gridmap const &gridmap() const;
+    void drawDebugVisual() const;
 
 private:
     DENG2_PRIVATE(d)