Define size/alignment for object, string, and any to be implementation-defined
1. Modify `GetOwnProperty` to account for arrays
1. Modify the constructors to be more fully defined
1. Define ConvertAndCopyTo routine that is more complete and somewhat more lenient

Still fairly informal, needs work to make it use spec language
Merge pull request #5 from nikomatsakis/arrays-and-more

Arrays and more