Time for action – power-ups

1. Add the following declarations to the WeaponManager module:

   Private _powerUps As List(Of Sprite)= New List(Of Sprite)
   Private _maxActivePowerups As Integer = 5
   Private _timeSinceLastPowerup As Single = 0.0
   Private _timeBetweenPowerups As Single = 2.0
   Private _rand As Random = new Random()

2. Add the tryToSpawnPowerup() method to the Weapons Management Methods region of the WeaponManager module:

   Private Sub tryToSpawnPowerup(
       x As Integer, 
       y As Integer, 
       type As WeaponType)
   
       If _powerUps.Count >= _maxActivePowerups Then
           Return
       End If
   
       Dim thisDestination As Rectangle = 
           TileMap.SquareWorldRectangle(New Vector2(x,y))
   
       For Each powerUp as Sprite in _powerUps
           If powerup.WorldRectangle = thisDestination Then
               Return
           End If
       Next
   
       If Not TileMap.IsWallTile(x,y) Then
           Dim newPowerup As Sprite = New Sprite(
               New Vector2(thisDestination.X, thisDestination.Y),
               Texture...