corrected doc error
make encryption button text more consistent
fix plugin name ThirdFlow

the icon may be slightly misleading but it's not the Third Wave and instead the Third Flow.
First pass at KaTeX plugin

Finally fixes #458 thanks to the KaTeX plugin from Khan Academy
Updates to KaTeX plugin
Add plugins to TOC on tw5.com
Include word "Version" in ribbon on tw5.com
Add dev docs to readme
Sort order for TOC on tw5.com
Update docs for select widget

How’s this @danielo515?
Readme update
Merge pull request #889 from pmario/fix-encryption-button-consistency

make encryption button text more consistent
Merge pull request #890 from TheDiveO/master

Minor: fix plugin name ThirdFlow
Merge pull request #854 from buggyj/tw2parserdocerr

corrected doc error
Release note update for 5.1.1
Merge pull request #894 from pmario/de-AT-DE-korrektor

some more german typos
typos found by ChrisK