Replace keepValue with better solution for translating values

[dxinteractive]

Addresses #264, #265

dataparcels

• Allow Parcel.metaAsParcel() to be passed the meta from the original parcel, and to pass changes to meta back to the original parcel
• Add dataparcels/translate to replace the functionality of ParcelBoundary's keepValue prop but in a way that supports multiple input instances, keep co-dependent code logic together, and uses far less code.

// before
let numberToString = parcel => parcel
    .modifyDown(number => `${number}`)
    .modifyUp(string => Number(string));

<ParcelBoundary parcel={myParcel.pipe(numberToString)} keepValue>

// after
let numberToString = translate({
    down: number => `${number}`
    up: string => Number(string),
    preserveInput: true
});

<ParcelBoundary parcel={myParcel.pipe(numberToString)}>

react-dataparcels

• BREAKING CHANGE removed ParcelBoundary's keepValue prop

To upgrade

• Find all keepValue, remove, use translate instead