1) The Insert functionality was changed in abebc6b to not delete
unfinished dynamic playlists anymore. "Play Next" has now been
added as an option when playback is stopped. The behavior of
"Play Next" as such has not changed and it is now the consistent
way to replace a current playlist in all playback modes.
2) The 'Insert' and 'Insert Shuffle' options will now only be
displayed if there is a resumable dynamic playlist
Change-Id: Ib5c5469b9e2c583ab06e0f47a922c24e5adf6b5f