Room and lobby chat, /host, /fashion, player-colored lines, context tips, and American spelling

- Chat goes to your room (the sandbox, or your game) by default, and to the whole lobby with /all or a leading !.
  Lines from elsewhere say where they came from ([Sandbox], [Game 2]), lobby-wide ones from your room say [All].
  Typing shows only to your room. Protocol 8.
- Hosting: everyone is told who hosts now, and the host can hand it over with /host "player".
- /fashion <item> wears a fashion locally, like /color.
- Lines that mention a player show in that player's color, looked up as they draw.
- Tips are tagged with the item and situations they fit, and those that fit are 1.5x as likely. They turn over every
  10 seconds on one continuous run, show under the menu too, and can be turned off with Tips in HUD / Gameplay. The
  HUD hotbars hide while the menu is up (except on its item tabs).
- American spelling throughout: color, center, gray, mustache, and so on.

src/game.h

@@ -20,7 +20,7 @@
 
 constexpr float PVP_OFF_SHADE = 0.4f;
 
-// How a fighter's colour is asked for: as it shows in the world (darkened when PvP keeps it out of this screen's
+// How a fighter's color is asked for: as it shows in the world (darkened when PvP keeps it out of this screen's
 // fights), or plain, as the HUD shows it.
 enum Tint
 {
@@ -85,7 +85,7 @@ struct Game
         return count;
     }
 
-    // A fighter's colour: its match colour (handed out when the match starts), or in the sandbox this screen's own
+    // A fighter's color: its match color (handed out when the match starts), or in the sandbox this screen's own
     // (picked in Profile, white while unassigned) until others join, when everyone
     // gets one. With others in the sandbox, everything of another fighter is darkened on this screen unless it and this
     // screen's own both have PvP on (so they can hurt each other); this screen's own always shows in full. Asked for