Adding new options for game-join and respawn equipment interval

[RedstoneFuture]

Fixing #102

• Adding new config options in the arena config
  • "start" option is now "custom_start_interval"; and now it's only for the game join (-1 if you wish to use the basic interval based on the team amount and the game time)
  • if "reset_after_respawn" is true the interval is resetting with death respawn
  • "custom_respawn_interval" is now only for the respawn interval (-1 if you wish to use the basic interval based on the team amount and the game time)

previous version:

equipment_interval:
  start: 10
  intervals_by_team_amount:
    "1": 15
    "2": 20
    "4": 25
  interval_factor_by_game_time:
    "1800": 1.0
    "300": 0.7
    "600": 0.8
    "900": 0.9

now:

equipment_interval:
  custom_start_interval: 10
  reset_after_respawn: true
  custom_respawn_interval: 10
  intervals_by_team_amount:
    "1": 15
    "2": 20
    "4": 25
  interval_factor_by_game_time:
    "1800": 1.0
    "300": 0.7
    "600": 0.8
    "900": 0.9