[geary: 2/2] Merge branch 'improve-plaintext-conversion' into 'master'

[Michael Gratton <mjog src gnome org>]

commit 03a18fbef02404db8b942c0fc228f9a09db821cc
Merge: 65116e0e 00da60de
Author: Michael Gratton <mike vee net>
Date:   Tue Jan 1 23:43:20 2019 +0000

    Merge branch 'improve-plaintext-conversion' into 'master'
    
    Delineate tags a, b, i, and u in plaintext conversion
    
    See merge request GNOME/geary!69

 test/client/composer/composer-web-view-test.vala |  26 ++++
 test/js/composer-page-state-test.vala            |  10 +-
 ui/composer-web-view.js                          | 174 +++++++++++++++--------
 3 files changed, 143 insertions(+), 67 deletions(-)
---