They can use the remove vote button or select the same option again for
single choice polls.
This commit refactor the plugin to properly organize code and make it
easier to follow.
* FIX: Show date picker over modal
Previously, scrolling was necessary to see the whole picker.
* FEATURE: Improve validation for polls
Adds new error messages for each of the edge cases. Previously, it
failed with a simple error saying that the minimum value must be less
than the maximum value.
* UX: Copy edit
Adds an optional title attribute to polls. The rationale for this addition is that polls themselves didn't contain context/question and relied on post body to explain them. That context wasn't always obvious (e.g. when there are multiple polls in a single post) or available (e.g. when you display the poll breakdown - you see the answers, but not the question)
As a side note, here's a word on how the poll plugin works:
> We have a markdown poll renderer, which we use in the builder UI and the composer preview, but… when you submit a post, raw markdown is cooked into html (twice), then we extract data from the generated html and save it to the database. When it's render time, we first display the cooked html poll, and then extract some data from that html, get the data from the post's JSON (and identify that poll using the extracted html stuff) to then render the poll using widgets and the JSON data.
