change array access code

[JosephLenton]

Array access code is slow, and needs optimizing, so that it can access the array element directly.

Specifically, remove the QubyArray class, and instead have it extend the standard Array prototype instead. So there is no array wrapper.

[JosephLenton]

Currently it uses a polymorphic 'quby_getCollection' to return values from a collection, and wraps arrays within a QubyArray.

An improved version could try adding the QubyArray functionality to the Array prototype, such as a 'quby_get' instead of 'quby_getCollection'. Generated code could also assert it exists, before access.