Remove three unused template tags.

Review Request #9253 - Created Oct. 9, 2017 and submitted

Christian Hammond
Review Board

The {% ifneatnumber %}, {% dashboard_entry %}, and
{% nav_active %} template tags haven't been used in a while, but the
code has remained. This change simply gets rid of them and the unit test
for {% ifneatnumber %}.

Unit tests pass.

Tested the administration UI, dashboard, and review request pages to make
sure nothing regressed.

David Trowbridge
Christian Hammond
Review request changed

Status: Closed (submitted)

Change Summary:

Pushed to release-3.0.x (3421b26)