Merge branch 'master' into v4

Conflicts:
	addon/comment/continuecomment.js
	lib/codemirror.js
        mode/puppet/puppet.js

Drop setLine and removeLine from the API

Mark release 3.21

Mark release 3.20

Mark release 3.19.0

Mark release 3.18

Mark release 3.17

Mark release 3.16.0

Mark release 3.15.0

Mark release 3.14.0