A range that lists every active resource.
Only resources that were reloaded are included when using [].
ResourceArena!int arena; arena.load(0); arena.load(1); arena.load(2); assert(arena.activeResources.equal([0, 1, 2])); // Observe the results as we reload the resources during the next cycle arena.startCycle(); assert(arena.activeResources.empty); arena.reload(0, 0); assert(arena.activeResources.equal([0])); arena.reload(2, 2); assert(arena.activeResources.equal([0, 2])); arena.reload(1, 1); assert(arena.activeResources.equal([0, 1, 2])); // Order of insertion
List every active resource in the arena. Omits expired resources.