Prework Milestone 4: Viewing all players

**Problem:**
I want to be able to see other players moving around.

**Implementation Suggestions:**
Blocked first by #8, #9 and #10 but once we have our game client described in the README with the map, our personal avatar and movement, we should also be able to display other player's avatars.

**Testing Criteria:**
Open index.html in Chrome and confirm that we can see other avatars moving

Review the game client description in README and the dependencies tracked by issues #8, #9, and #10 before inspecting index.html. Use the existing map, personal avatar, and movement work as context. Done means opening index.html in Chrome and confirming that other player avatars are visible and moving.

Written by the indexing model from the issue text.