Added the ability to set x y and z of a merc tile after initialization

src/vector_tile_merc_tile.hpp

@@ -43,16 +43,34 @@ class merc_tile : public tile
     {
         return x_;
     }
+
+    void x(std::uint32_t x)
+    {
+        x_ = x;
+        extent_ = merc_extent(tile_size_, x_, y_, z_);
+    }
 
     std::uint32_t y() const
     {
         return y_;
     }
 
+    void y(std::uint32_t y)
+    {
+        y_ = y;
+        extent_ = merc_extent(tile_size_, x_, y_, z_);
+    }
+
     std::uint32_t z() const
     {
         return z_;
     }
+
+    void z(std::uint32_t z)
+    {
+        z_ = z;
+        extent_ = merc_extent(tile_size_, x_, y_, z_);
+    }
 };
 
 typedef std::shared_ptr<merc_tile> merc_tile_ptr;

src/vector_tile_tile.hpp

@@ -26,7 +26,7 @@ class tile_layer;
 
 class tile
 {
-private:
+protected:
     std::string buffer_;
     std::set<std::string> painted_layers_;
     std::set<std::string> empty_layers_;