make approved deletions visually distinct

[Craig Berry]

A word deleted via annotation and then approved is displayed highlighted in green just like any other annotation. It might be clearer if the fact that it's a deletion were shown some other way, such as strikethrough instead of highlight or red strikethrough plus green highlight.

[Craig Berry]

Addressed with the following change in the annotation client:

#!

commit 7254748356ae634da36951ad8c41f6b296239d01 (HEAD -> master)
Author: Craig A. Berry <[e-mail]>
Date:   Sat Jun 9 12:22:25 2018 -0500

    Flag deletions with strikethrough.

    This addresses Issue #48 in the annopub issue tracker.  That
    ticket actually mentioned approved deletions, but it seems
    reasonable to make both unapproved and approved deletions
    visually distinct. Now they are.