added new overloaded constructor options to match TypedArray pattern

[zipzapzanigan]

added additional overloaded arguments to accomodate byteOffset and length at init to match the TypedArray constructor pattern

new TypedArray(buffer)
new TypedArray(buffer, byteOffset)
new TypedArray(buffer, byteOffset, length)

also added a few test cases to cover the new constructor patterns, with various lengths of arrays, as well as testing byteOffset to ensure it offsets by 8 bits per byte

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray#constructor

closes #1

[swiing]

I am going to close this PR for the following reasons:

1. as said here, I need a compelling argument why ByteOffset would make sense for bit arrays.

2. even if we would like to allow byteOffset/length, the code does not comply to the standard.
   E.g. new BitArray("011010", 0, 9).length === 9 should be false, not true. In order to convince you, check new Uint32Array([0,1,1,0,1,0], 0, 9).length (the value of which is 6, not 9). This is because the proposed code applies byteOffset/length to iterables, not to ArrayBuffers.

Anyway, thanks for sharing this. It raises interesting considerations.