Improve naming of entry-related Less variables and move to defs.less.

Review Request #9175 - Created Sept. 6, 2017 and submitted

Christian Hammond
Review Board

This moves the entry-related variables out of reviews.less and into
defs.less, renaming them in the process in order to have a more
consistent naming scheme and to make these available to extensions that
may want to reference them. No actual styling has changed.

Tested that the entries still render correctly.

David Trowbridge
Christian Hammond
Review request changed

Status: Closed (submitted)

Change Summary:

Pushed to release-3.0.x (504ae99)