fixed plugin doc
assets/myplugin.js.txt read "destroy() will call initializer()"
Fixed ButtonGroup.enable()
the `disabledChange` listener always disabled the buttons, never enabled them
panel: Change link to icon source files, fix #1335
Merge branch 'myplugin-docfix' into live-docs
Merge branch 'live-docs' into dev-master
frame: Update HISTORY.md with #1367
Merge remote-tracking branch 'asystance/buttongroup-enablefix' into dev-master
button-group: Build - fix #1374
button-group: Update HISTORY.md with #1374