[BUG #8613] first steps into consolidation of bom.Xhr and io.Xhr
[BUG #8613] rewrite bom.Xhr tests to io.Xhr tests
[BUG #8613] rectify API of AbstractRequest
[BUG #8613] consolidate bom.Jsonp and io.Jsonp
[BUG #8613] move and adapt bom to io
[BUG #8613] more consolidation adaptions
[BUG #8613] remove bom namespace