fix a rare crash related to decoration spawn

CoalaAreaDecorationConfiguration

• add smothSpawning checkbox

  • spawn decorations for this config entry all at once or slowly to keep the framerate up

BP_Coala

• add field "Count max parallel areas creating"

  • This value defines how many areas/chunks are simultaneously generated in your map. Increasing this value could have a negative performance impact on the device. Default value is 3.