Add macro removeblock_iter()

When we switch blocks to not use 'active', we'll need this macro to
remove blocks while iterating through the vector, one at a time,
forwards.

desktop_version/src/Entity.h

@@ -9,6 +9,7 @@
 #include <string>
 
 #define removeentity_iter(index) { obj.removeentity(index); index--; }
+#define removeblock_iter(index) { obj.removeblock(index); index--; }
 
 enum
 {