Check if referenced replies and retweets actually exist #226
Description
What’s missing?
When validating tweets, make a request to twitter to ensure that any retweet or reply links really exist.
Why?
This feature would help prevent tweets from being merged if the tweets they reference don't exist. Currently, any correctly formatted tweet URL is accepted regardless of ID, which could cause the subsequent push action to fail and repo state to be out of sync, causing confusion.
Ref #224