some much needed updates to docs using roxygen 4.0.0
dealt with case where 'lesson' file has no extension
removed test lesson from swirl -> swirl_courses repo
Documented answerTests2.R and roxygenized.
minor corrections to documentation
a couple small tweaks to output
fixed message and hardcoded course_name
add check for incorrect - i.e. empty result
fixed small bug in content
small tweak to coursera code
changed message received if too many skips
updated course menu blurb
Improved cheat resistance.
fixed manual submission
Suppressed warnings and messages in the two places which currently matter: saveEval and skip processing.
Merge branch 'master' into coursera
Merge remote-tracking branch 'upstream/master' into dependson