server: listen 8080 if executed directly (not required)
server: serve learning.json with varying wilting count
use learning.json served locally; remove from manifest when released
add ability to override wilting count sent by server
server: add a nologin param for testing 403
main: show notifications sometimes when wilting count updates
fix single line if statements
Memrise: only add to url if params has something
opts: fix bad html
Memrise: fix params checks
processGroups: return undefined unless wilting > 0
Notification: add event listener for click only if url is defined
opts: add notifications

- settings storage not implemented
don't use mock data
make icon{48,128}.png transparent and bigger
define USE_MOCK_DATA in main.js so that tests don't fail
show pictures in notifications (windows only)
opts: validate wilting-threshold in settings
update rivets
opts: add notifications configuration