Add functionalities

[amasson42]

• initiablebyarrayliteral when element is comparable
• init with sorted assert the array is sorted\
• subscript accessor is settable
• add reserveCapacity method
• use index type instead of int

[ole]

@amasson42 Thank you for your PR. I'm very sorry that it took me more than a year to take a look at this and respond. As you undoubtedly noticed, I have neglected to maintain this library for years.

I looked over your changes briefly. I like some of them and some not so much. For example, I'm not sure the mutable subscript is a good idea. Regardless, I'm not going to merge this right now because I first have to make up my mind what I want to do with this library, i.e. whether I want to maintain it at all. Sorry again.