range emitter using levelup ranges.
Inspired by multileveldown
var re = require('range-emitter')range in the format of ltgt
cb callback(key, type) type can be put or delete
resend if true will resend the subscriptions to the server
key single key to subscribe to
cb callback(key, type) type can be put or delete
resend if true will resend the subscriptions to the server
subscribe to all keys
cb callback(key, type) type can be put or delete
resend if true will resend the subscriptions to the server
unsubscribe a range or key