added "test" mode for testing a specific lesson
updated documentation using roxygen2 v4.0.0
some more tweaks to test lesson feature
accidentally branched from wrong place - correcting
added check so we don't return to course menu in test mode
exempted swirlify from double evaluation
replace path.package() with system.file() everywhere in swirl
Merge branch 'master' into testlesson
added progress bar feature
Merge branch 'master' into testlesson
fixed method name
fix some spacing issues
remove all remnants of course authoring code
changed goodbye message for test mode
changed goodbye message for test mode
Merge branch 'master' into rm-author
Removed "dev" mode.
Removed courses from package. Added menu which offers to install suggested courses, or to direct user to swirl_courses for manual installation.
A few bug fixes and traps for situations in which the internet is unavailable.
removing cruft