Unapplied rules

In #85, the following rule should simply the `Int2Bytes` function, but it doesn't work as expected.

```
  rule [int2bytes-concat]:
    Int2Bytes ( 1 , X:Int &Int 255 , LE ) +Bytes Int2Bytes ( 1 , X:Int >>Int 8 &Int 255 , LE ) +Bytes Int2Bytes ( 1 , X:Int >>Int 8 >>Int 8 &Int 255 , LE ) +Bytes Int2Bytes ( 1 , X:Int >>Int 8 >>Int 8 >>Int 8 , LE )
    => Int2Bytes(4, X, LE)
    [simplification]
```
