migrate from buffer to Uint8Array

[bhaveshg16]

the following PR fixes #51 .
test script contained some instance of buffer which i shifted to Uint8Array.
uint8array-tools library has also been used to make things easier.

[bhaveshg16]

I have kept naming conventions as it is.. LMK if that has to be changed @junderw

[junderw]

Thanks for getting started.

Here are a few suggestions to get the ball rolling.

You can also start a pull request to add any other tools you think might be useful (that you see used a lot with Buffers, but can't find an equivalent for Uint8Array) to the uint8array-tools library.

[junderw]

Suggested change

	const bytes = new Uint8Array(Buffer.from(bech32.fromWords(f.words)));
	const bytes = Uint8Array.from(bech32.fromWords(f.words));

[bhaveshg16]

the change that u suggested would give a 0 value for any latin character. we will have to initialise a new Uint8Array instance.
or write it like:

 const bytes = Uint8Array.from(Buffer.from(bech32.fromWords(f.words)));

If we want to completely eliminate every instance of buffer here, one thing I can do is create a function for the same in uint8array-tools library or keep it the same as i did.

[junderw]

Suggested change

	t.same(Buffer.from(bytes).toString('hex'), f.hex);
	t.same(uint8arraytools.toHex(bytes), f.hex);

[bhaveshg16]

also in code there are requirements to convert typedArray to string in 'utf8' or 'binary' format. Whereas uint8array-tools library only provides to convert it to 'hex' format. I'll proceed with adding those two feature as well in that library

[bhaveshg16]

Hey @junderw all requested changes have been made.
For now i Have installed "uint8array-tools" library from my forked repo.
please review it.