This hook had a bug where you couldn't select text because every
time you push a button, including ctrl+a or shift+left/right, the
cursor position gets reset and then deselects immediately.
So let's only reset the content and cursor only when text changes,
so arrow keys and ctrl don't have any negative effects.
Unfortunately, when adjusting the box's value, it causes the datalist
to disappear, and it only comes back after you press another key.
I can't figure out how to make the datalist reappear automatically
with js.
The javascript is very inconsistent between pages. I'm trying to
start using a consistent pattern where the api call is kept in a
separate function from the ones that buttons and input boxes
talk to.
Instead of embedding the entire tag list in the search.html template
every single time, this script loads the tags from the new,
cache-enabled endpoint /all_tags.json. Then we can use html5
datalists to create autocomplete forms on the search and photo pages.
