In-place TODO comments outlining a "snapshot" strategy for resolving issue #39.
Merge branch 'master' into ftr.snapshots
resolved trivial merge conflict

Merge branch 'master' into ftr.snapshots

Conflicts:
	R/menu.R
take snapshots and use them in restoring progress
in progress
Merge branch 'master' into ftr.snapshots
Fixed conflict with master
safeEval evaluates an epression in a protected environment whose parent is global. Used in several places.
Merge branch 'master' into ftr.snapshots
Merge branch 'master' into ftr.snapshots
Fct to create clean environment whose parent is a snapshot of the global environment at a previous time.
Function to create clean environment whose parent simulates previous user environment.
Cleanup, including trivial merge conflict with current master, and some TODO: comments.

Merge branch 'master' into ftr.snapshots

Conflicts:
	R/answerTests.R
Merge branch 'master' into ftr.snapshots
Merge branch 'master' into ftr.snapshots
Merge branch 'master' into ftr.snapshots
Merge branch 'master' into ftr.snapshots
Deleted creates_var() expectation as obsolete in this branch. Fixed various things related to creation of new variables combined with skipping questions.
Better treatment of newVar/skip issue
Finishing touches on prototype, "snapshot," mostly commentary. Also, restore global from snapshot after failing answer tests in case user has garbled environment.
Merge branch 'master' into snapshots