Add polls (#10111)

* Add polls

Fix #1629

* Add tests

* Fixes

* Change API for creating polls

* Use name instead of content for votes

* Remove poll validation for remote polls

* Add polls to public pages

* When updating the poll, update options just in case they were changed

* Fix public pages showing both poll and other media

app/javascript/mastodon/reducers/polls.js

@@ -0,0 +1,19 @@
+import { POLL_VOTE_SUCCESS, POLL_FETCH_SUCCESS } from 'mastodon/actions/polls';
+import { POLLS_IMPORT } from 'mastodon/actions/importer';
+import { Map as ImmutableMap, fromJS } from 'immutable';
+
+const importPolls = (state, polls) => state.withMutations(map => polls.forEach(poll => map.set(poll.id, fromJS(poll))));
+
+const initialState = ImmutableMap();
+
+export default function polls(state = initialState, action) {
+  switch(action.type) {
+  case POLLS_IMPORT:
+    return importPolls(state, action.polls);
+  case POLL_VOTE_SUCCESS:
+  case POLL_FETCH_SUCCESS:
+    return importPolls(state, [action.poll]);
+  default:
+    return state;
+  }
+}