initial implementation of alert component
Merge branch 'master' into alert
Alert: better layout choice
Release notes: added section for deprecated APIs.
TextInput: search alternate name (closes #534)
PickerList: better disposal
Label: sets the proper text renderer height (closes #663)
Merge branch 'master' into alert
Alert: more docs and better API naming
Callout: show() supports a custom overlay factory
Merge branch 'master' into alert