Decode streams into strings without setEncoding

``js
const fs = require('fs')
const zlib = require('zlib')
const strs = require('stringstream')

const utf8Stream = fs.createReadStream('massiveLogFile.gz')
.pipe(zlib.createGunzip())
.pipe(strs('utf8'))

utf8Stream.on('data', str => console.log(This will be a string: ${str}))
`

API

- strs(to, [options]) – creates a transform stream that converts the input into strings in to encoding (eg, utf8, hex, base64)
- strs(from, to, [options]) – creates a transform stream converts the input from strings in from encoding to strings in to encoding

options can be anything compatible with the standard Node.js [new stream.Transform([options]) constructor](https://nodejs.org/api/stream.html#stream_new_stream_transform_options)

NB: This library was originally written before Node.js correctly encoded base64 strings from streams

Back in the day, calling .setEncoding('base64') on a readable stream didn't
align correctly, which was one of the main reasons I wrote this library –
however this hasn't been the case for a long time, so this library is
now really only useful in scenarios where you don't want to call
.setEncoding() for whatever reason.

It also handles input and output text encodings:

`js
// Stream from utf8 to hex to base64... Why not, ay.
const hex64Stream = fs.createReadStream('myFile.txt')
.pipe(strs('utf8', 'hex'))
.pipe(strs('hex', 'base64'))
`

Also deals with base64 output correctly by aligning each emitted data
chunk so that there are no dangling = characters:

`js
const stream = fs.createReadStream('myFile.jpg').pipe(strs('base64'))

let base64Str = ''

stream.on('data', data => base64Str += data)
stream.on('end', () => {
console.log('My base64 encoded file is: ' + base64Str)
console.log('Original file is: ' + Buffer.from(base64Str, 'base64'))
})
``