Improve track of storage reference

[montyly]

In the following example, both contracts have the same outcome, but slither detects an initialized variable in Reference:

contract Reference{
    mapping (uint128 => mapping (uint256 => uint256)) map;

    function init() external{
        mapping(uint256 => uint256) tmp = map[0];
        tmp[0] = 0;
    }
}

contract Direct{
    mapping (uint128 => mapping (uint256 => uint256)) map;
    
    function init() external{
        map[0][0] = 0;
    }
}

The issue is that slither does not track the storage reference created through mapping(uint256 => uint256) tmp = map[0];, while it should.

It is close to the issue #70

[montyly]

The alias analysis is merged in master, this FP is not anymore reported