initialize x, y, bound.y in constructor

This change sets a Rec2's x, y and bound.y in constructor.

Open node console in rec2's root dir and run this to see issue

    var assert = require('assert')
    var Rec2 = require('./')
    
    var r = new Rec2(1, 2, 3, 4)
    
    assert.equal(r.x, 1)
    assert.equal(r.y, 2)
    
    assert.equal(r.bound.x, 1 + 3)
    assert.equal(r.bound.y, 2 + 4)