Short-circuit semantics of boolean operators

[bitbart]

Modify the semantics of TinySol so that the evaluation of boolean operators is short-circuited:

https://docs.soliditylang.org/en/latest/types.html#booleans

For example, in the following contract:

contract C {  
      uint x;
      function f() public { if (x==1 || this.g()==1) x+=1; else x=5; }
      function g() public view returns(uint) { require(x==0); return 1; } 
 }

executing two successive calls to the function f should yield x==2, since in the second transaction the first condition x==1 is true, and so there is no need to perform the call to g.

Similarly, in the contract:

contract C {  
      uint x;
      function f() public { if (x==0 && this.g()==1) x=1; else x=5; }
      function g() public view returns(uint) { require(x==0); return 1; }
}

executing two successive calls to f should yield x==5, since in the second transaction the first condition x==0 is false, and so there is no need to perform the call to g.