add conditional recalc for extreme expectations
add extreme expectation calculation tests
add extreme, positive cases to expectation test

- now test uses region of support ranging from 0 to 37 SDs away from mean
try calculate variance for mirror setup for extreme support
test for good variance calculation behavior

- tests now include region of support from 0 to 37 sds away in both directions
test tests for positive variances
bump version to 0.1-8
update using vign