Refs #8953 - Retrieve monitor correctly when setting geometry details.

No longer fail silently in the case of an error.  Be a bit more
const-correct.

Add some asserts that hopefully make sense in the context of the function.
Re #9030. Removed unused classes.
Re #9030. Use covariance matrix to estimate errors of calc. values
Merge remote-tracking branch 'origin/bugfix/8953_populate_geometry_tab_correctly'