Echidna printer: constant propagation over parameters init

```solidity
contract A{
uint a;
constructor(uint param) public {
a = param;
}

function f() public (uint){
return a + 10;
}

}

contract B is A{
constructor() public A(10){ }
}
```

We could use `A(10)` to do additional constant propagation in `f()`

The issue names the Echidna printer but no file or test. Begin by locating its constant-propagation entry point and tracing how inherited constructor arguments are represented; use the Solidity example as the regression case, with completion meaning A(10) lets the printer recognize a as constant in f().

Written by the indexing model from the issue text.