Added user stats for single arena
Methods in IUserStatsManager has been marked as deprecated.
Added placeholders:
- %minipvp_arena_player_destroyed_hearts_<arena_name>%
- %minipvp_arena_player_wins_<arena_name>%
- %minipvp_arena_player_defeats_<arena_name>%
- %minipvp_arena_player_kills_<arena_name>%
- %minipvp_arena_player_deaths_<arena_name>%
- %minipvp_arena_player_games_played_<arena_name>%

The plugin requires 1.5 T-DataBasesApi version