Revise Accessible::decode() to handle ignored properties.

Add a 2nd parameter to Accessible::decode() as the list of ignored
properties.

The list is defaulted to empty.

Also, revised Accessible::decode() to warn when a property from the file
does not have a corresponding decoder. It also outputs a INFO when a
property with empty value is supplied.
Update warning message
Merge branch 'master' into feature/accessible-decode-revision
Merge branch 'feature/accessible-decode-revision' into 'master'

Accessible::decode revision

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1168343