Automatically initialise new attributes

[Enchufa2]

E.g.,

library(simmer)

t <- trajectory() %>%
  set_attribute("asdf", 1, mod="+", init=10) %>%
  set_global("fdsa", 2, mod="+") # init=0 by default

simmer() %>%
  add_generator("dummy", t, at(0), mon=2) %>%
  run() %>%
  get_mon_attributes()
#>   time   name  key value replication
#> 1    0 dummy0 asdf    11           1
#> 2    0        fdsa     2           1

[codecov]

Codecov Report

Merging #157 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #157   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          50     50           
  Lines        2832   2833    +1     
=====================================
+ Hits         2832   2833    +1

Impacted Files	Coverage Δ
inst/include/simmer/activity.h	100% <ø> (ø)	⬆️
R/trajectory-activities.R	100% <100%> (ø)	⬆️
inst/include/simmer/activity/arrival.h	100% <100%> (ø)	⬆️
src/activity.cpp	100% <100%> (ø)	⬆️
R/trajectory-class.R	100% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6e70ad5...e65a9ce. Read the comment docs.