Add an option to load the data files

[leoniedu]

Even with medium sized data files, load_all takes a significant time to load. Could an option to load the data be added?

Something like:

load_all <- function(path = ".", reset = TRUE, compile = NA, attach = TRUE, export_all = TRUE, export_imports = export_all, helpers = export_all, attach_testthat = uses_testthat(path), quiet = NULL, recompile = FALSE, warn_conflicts = TRUE, load_data = TRUE) ... if (load_data) out$data <- load_data(path) ...