Addition operation uses wrong mov command

```
def main
var b = 2
var a = b + 0
end
```

should produce this asm code

```
mvi a, 02
sta 0810
lda 0810
adi 00
;or with mov a,a
sta 0811
hlt
```

but instead produces this, probably due to wrong offset in byte code
```
mvi a, 02
sta 0810
lda 0810
adi 00
mov a, b
sta 0811
hlt
```