Round-robin state is not shared among generators

[Enchufa2]

We either document this behaviour or fix it:

library(simmer)

t <- trajectory() %>%
  select(paste("res", 1:2), policy="round-robin") %>%
  log_(function() get_selected(env))

env <- simmer() %>%
  add_resource(paste("res", 1:2)) %>%
  add_generator("dummy", t, at(0, 0))

invisible(run(env))
#> 0: dummy0: res 1
#> 0: dummy1: res 2

vs.

env <- simmer() %>%
  add_resource(paste("res", 1:2)) %>%
  add_generator("dummy0", t, at(0)) %>%
  add_generator("dummy1", t, at(0))

invisible(run(env))
#> 0: dummy00: res 1
#> 0: dummy10: res 1

A user bitten by this.