Migrated to IntelliJ/gradle
PlayerService: use Builder for notification
res: added ic_notif icon

Based on the clone of original one; black&white.
PlayerService: more wip, resolved some errs
PlayerService: now builds
DDF: external player on long click

And prepared for launching internal player on short click
PS: rearranged
Launch PlayerService from DDF
PS: do show notification, and make it ongoing
PS: notification compat, content intent
Added action_next icon
PS: "Next" button in notification
PS: initial actions