attach_source() now allows the R scripts to contain library() calls, and have
functions defined in the script "see" the library() calls. R scripts are now
first sourced into a new.env(parent = .GlobalEnv), and then all symbols are
subsequently copied over into a (different) attached environment. You can restore
the old behavior, where the scripts are evaluated in an already attached environment,
with attach_source(parent = NULL).attach_source() now allows scripts to define a .mask.OK object to a character
vector of names of objects that shouldn't be warned about when warn.conflicts=TRUE.
attach_source() now respects the existence of .conflicts.OK, matching the
behavior of attach().
attach_source() gains a parent argument, allow customizing the parent of
the environment where scripts will be evaluated. (default, .GlobalEnv)
import_from would not resolve reexported objects from packages.NEWS.md file to track changes to the package.