Fixes test failures with testthat 2.0.0
with_file() function to automatically remove files.
with_connection() function to automatically close R file connections.
with_db_connection() function to automatically disconnect from DBI database connections.
with_gctorture2 command to run code with gctorture2, useful for testing (#47).
with_environment()(and equivalent locals) functions added, to run code with a modified object search path (#38,
code argument from
local_ functions (#50).
assignmentargument to allow specifying additional assignment types.