Added support for starring.
Stores recation events in a reactionMap, so rendering can use it
later.
Improved reply to replies, by keeping a separate replyDomMap.
Changed from heart to star, reason: thumbsup or a heart are good
for positive events, but not so suitable to react to a bad event.
So currently negavtive votes are just counted as a star as well.
Did not add another dom map, but just querySelector in case an
existing star needs to be updated later.
Used different CSS-only tab technique. The implementation before
messed up the whole height of the page and used unnecessary
absolute positioning.
Added comment icon from MFG Labs iconset (SIL)
- https://github.com/MfgLabs/mfglabs-iconset
Added outlined and filled heart from Elusiv icons (SIL)
- https://github.com/dovy/elusive-iconfont
Time ago seconds should be rounded.