Start implementing the new look (and feel)

- Add the first batch of the new graphics
- Add a knight entity
- Add new music (8 bit rebel)
- Remove temporary sprites
- Remove unused sound effects
Add new player and flag sprites

- Add two more teams (now 4 in total)
- Move all entity creation to the entity factory on the server
- Add temporary attack animation (scaled)
Add new map (castle)

- Change to calculate game width and height from the tilemap data
Merge branch 'feature/new-look' into develop