implement new operator for solidity 0.7.1

[jacky860226]

Implement new for solidity 0.7.1
For example, the following contracts can be supported:

contract AAA{
	BBB b;
	function func() public returns(int){
		b = new BBB();
		return b.func2();
	}
}
contract BBB{
	function func2() public returns(int){
		return 7122;
	}
}