Fix wall blocks being replaceable, e.g. by tree growing

Fixes #350

Author: davenonymous

src/main/java/org/dave/compactmachines3/block/BlockProtected.java

@@ -50,6 +50,15 @@ public boolean canEntityDestroy(IBlockState state, IBlockAccess world, BlockPos
         return super.canEntityDestroy(state, world, pos, entity);
     }
 
+    @Override
+    public boolean isReplaceable(IBlockAccess world, BlockPos pos) {
+        if(isBlockProtected(world.getBlockState(pos), world, pos)) {
+            return false;
+        }
+
+        return super.isReplaceable(world, pos);
+    }
+
     @Override
     public boolean canBeReplacedByLeaves(IBlockState state, IBlockAccess world, BlockPos pos) {
         if(isBlockProtected(state, world, pos)) {