Move entityclass::setblockcolour() to blockclass::setblockcolour()

This moves the function setblockcolour(), so I can directly call it on a
particular block without having to have it be inside obj.blocks.

desktop_version/src/BlockV.h

@@ -12,6 +12,8 @@ public:
     void clear();
 
     void rectset(const int xi, const int yi, const int wi, const int hi);
+
+    void setblockcolour(std::string col);
 public:
     //Fundamentals
     bool active;