generate default constructors for contracts that don't have any

[ivoysey]

This PR implements the production of default constructors for contracts that have no constructor. For example, on the test case

    contract TwoIntContainer{
        int x;
        int a;

        transaction set(int value) {
            x = value;
            a = value*value;
        }

        transaction get() returns int{
            return x+a;
        }
    }

    main contract ICGeneratedCons{
        int f;
        TwoIntContainer@Owned ic1;
        TwoIntContainer@Owned ic2;
        int x;

        transaction main() returns int{
            return (10);
        }
    }

you get

    function ICGeneratedCons___ICGeneratedCons0xfa583fc4(this, con_arg__f, con_arg_ic1_x, con_arg_ic1_a, con_arg_ic2_x, con_arg_ic2_a, con_arg__x) {
        // default constructor generated by the compiler
        // this.f := con_arg__f
        switch gt(add(this, 0), shl(255, 1))
        case true {sstore(add(this, 0), con_arg__f)}
        case false {mstore(add(this, 0), con_arg__f)}

        let _tmp_2 := allocate_memory(64)
        TwoIntContainer___TwoIntContainer0x5b1f0346(_tmp_2, con_arg_ic1_x, con_arg_ic1_a)
        let _tmp_1 := allocate_memory(64)
        TwoIntContainer___TwoIntContainer0x5b1f0346(_tmp_1, con_arg_ic2_x, con_arg_ic2_a)

        // this.x := con_arg__x
        switch gt(add(this, 96), shl(255, 1))
        case true {sstore(add(this, 96), con_arg__x)}
        case false {mstore(add(this, 96), con_arg__x)}
    }


    function TwoIntContainer___TwoIntContainer0x5b1f0346(this, con_arg__x, con_arg__a) {
        // default constructor generated by the compiler
        // this.x := con_arg__x
        switch gt(add(this, 0), shl(255, 1))
        case true {sstore(add(this, 0), con_arg__x)}
        case false {mstore(add(this, 0), con_arg__x)}

        // this.a := con_arg__a
        switch gt(add(this, 32), shl(255, 1))
        case true {sstore(add(this, 32), con_arg__a)}
        case false {mstore(add(this, 32), con_arg__a)}
    }

As house keeping matters this PR also includes

• more uniform naming of transactions in the flattened object
• an update to the test harness to be able to call transactions from the main contract with this change
• removing a needless boolean variable threaded through translation to indicate if the current scope is from the main contract or not
• documentation and helper functions in the utility file
• general code hygiene