Fix #218 Fix #213 Fix #192 Fix #191 Fix #211

- switch arm (#191)
- reset data
- show data (#192)

Fix #218, re #219:  uses a `liveforever` prefs.  Perhaps have a
deathtime pref woudl be better?  The assumption is that, for safety, the
default addon dies.  I am not sure if this is right or not.  Building
for experient AND feature is hard!
Merge pull request #213 from gregglind/b213-reset-switch-arms

add about:addon package.json