Enable production entities to autoqueue.
This adds a new command button that enables training of units automatically.
Use:
- Enable auto-queue.
- Train an entity.
This adds a new item to the queue whenever the previous item starts, such that good micro is more resource-efficient.
Patch by: @azayrahmad
Differential revision: https://code.wildfiregames.com/D3865
Comments by: @Langbart, @nani, @Stan, @wraitii