#1381 Warn about mismatched single braces in notes/synopses

[Ahasuerus]

At this time the yellow warning/cleanup report logic only checks for mismatched double braces in Notes/Synopses, which usually indicates invalid template syntax. It turns out that we also over 60 notes/synopses with mismatched single braces, which are uniformly in error. We need to change the yellow warning logic as well as the cleanup report logic to look for single brace mismatches instead of double braces mismatches. The cleanup report name needs to be changed from "Mismatched Template Braces" to "Mismatched Braces".

[Ahasuerus]

Implemented in:

common/library.py
common/viewers.py
edit/cleanup_lib.py
edit/cleanup_report.py
nightly/nightly_job.py

Installed in SVN 580 on 2020-11-27. Closing the FR.