Almost all assurance are unnecessary any more!!
add checkbox `start` and `finish` on `notifications-stay-visible`.
`notifications-stay-visible` will judged as `false` when given invalid key.
will used as `others` when given invalid `startOrFinish` option.
add notification offset setting
add explanation of badge setting
Merge pull request #210 from otiai10/feature/notification-offset-setting

Feature/notification offset setting
config UI `notification-stay-visible` change `input` to `select`.
merge upstream/develop
merge upstream/develop again.
merge upstream/develop again.
refactor select element
Merge pull request #209 from senda-akiha/extend-staying-notifications

Extend options for staying notifications
avoid legacy boolean config
more safety code
add judge widget url
Merge pull request #213 from senda-akiha/bugfix/widget-judge

add judge widget url
Merge pull request #212 from senda-akiha/extend-staying-notifications

avoid legacy boolean config for notification-stay-visible
add debug comment
edit after

Conflicts:
	src/js/pages/edittimer.js