simplify album-adding by marking itime as album
simplify album-adding by marking itime as album

Since both albums and items have an itime field, I'm putting itime into
ALBUM_KEYS_ITEM. This simplifies a lot of handling code. It also will make the
item and album itimes synchronize at some points, which is probably fine -- I
can't see a major use case for maintaining separate added dates for an album
and its tracks.

lightwang1/beets,madmouser1/beets,gabrielaraujof/beets,ruippeixotog/beets,asteven/beets,LordSputnik/beets,mosesfistos1/beetbox,swt30/beets,pkess/beets,arabenjamin/beets,moodboom/beets,krig/beets,untitaker/beets,untitaker/beets,sadatay/beets,jmwatte/beets,shamangeorge/beets,ibmibmibm/beets,sampsyo/beets,arabenjamin/beets,jbaiter/beets,mathstuf/beets,randybias/beets,lengtche/beets,parapente/beets,YetAnotherNerd/beets,jcoady9/beets,Andypsamp/CODjunit,multikatt/beets,bj-yinyan/beets,beetbox/beets,ttsda/beets,imsparsh/beets,gabrielaraujof/beets,Andypsamp/CODjunit,Freso/beets,untitaker/beets,moodboom/beets,SusannaMaria/beets,Dishwishy/beets,lightwang1/beets,marcuskrahl/beets,Andypsamp/CODfinalJUNIT,gabrielaraujof/beets,MyTunesFreeMusic/privacy-policy,tima/beets,dfc/beets,jcoady9/beets,ttsda/beets,ibmibmibm/beets,beetbox/beets,kareemallen/beets,bj-yinyan/beets,madmouser1/beets,pkess/beets,ruippeixotog/beets,drm00/beets,madmouser1/beets,krig/beets,ruippeixotog/beets,xsteadfastx/beets,jayme-github/beets,PierreRust/beets,Freso/beets,shamangeorge/beets,MyTunesFreeMusic/privacy-policy,LordSputnik/beets,jbaiter/beets,m-urban/beets,bj-yinyan/beets,LordSputnik/beets,Wen777/beets,multikatt/beets,jmwatte/beets,ibmibmibm/beets,YetAnotherNerd/beets,m-urban/beets,Dishwishy/beets,SusannaMaria/beets,Kraymer/beets,swt30/beets,xsteadfastx/beets,imsparsh/beets,Andypsamp/CODfinalJUNIT,artemutin/beets,jackwilsdon/beets,sampsyo/beets,YetAnotherNerd/beets,jcoady9/beets,moodboom/beets,shanemikel/beets,shanemikel/beets,diego-plan9/beets,Andypsamp/CODjunit,YetAnotherNerd/beets,krig/beets,mathstuf/beets,mosesfistos1/beetbox,marcuskrahl/beets,lightwang1/beets,dfc/beets,PierreRust/beets,jmwatte/beets,Andypsamp/CODfinalJUNIT,andremiller/beets,artemutin/beets,kareemallen/beets,sadatay/beets,jayme-github/beets,randybias/beets,kelvinhammond/beets,artemutin/beets,PierreRust/beets,xsteadfastx/beets,sadatay/beets,m-urban/beets,shamangeorge/beets,SusannaMaria/beets,marcuskrahl/beets,MyTunesFreeMusic/privacy-policy,kareemallen/beets,kelvinhammond/beets,mathstuf/beets,kareemallen/beets,andremiller/beets,Andypsamp/CODjunit,dfc/beets,m-urban/beets,diego-plan9/beets,jackwilsdon/beets,xsteadfastx/beets,moodboom/beets,kelvinhammond/beets,asteven/beets,multikatt/beets,lengtche/beets,andremiller/beets,Andypsamp/CODfinalJUNIT,gabrielaraujof/beets,Freso/beets,ttsda/beets,bj-yinyan/beets,mathstuf/beets,jmwatte/beets,mried/beets,Wen777/beets,jackwilsdon/beets,Freso/beets,pkess/beets,diego-plan9/beets,mried/beets,Kraymer/beets,randybias/beets,swt30/beets,drm00/beets,lengtche/beets,marcuskrahl/beets,Kraymer/beets,SusannaMaria/beets,artemutin/beets,ttsda/beets,diego-plan9/beets,multikatt/beets,LordSputnik/beets,randybias/beets,Kraymer/beets,kelvinhammond/beets,Andypsamp/CODjunit,pkess/beets,parapente/beets,dfc/beets,sampsyo/beets,lightwang1/beets,arabenjamin/beets,ruippeixotog/beets,jackwilsdon/beets,drm00/beets,jcoady9/beets,shanemikel/beets,tima/beets,Andypsamp/CODfinalJUNIT,MyTunesFreeMusic/privacy-policy,tima/beets,asteven/beets,parapente/beets,mried/beets,mosesfistos1/beetbox,sadatay/beets,sampsyo/beets,Wen777/beets,swt30/beets,ibmibmibm/beets,lengtche/beets,asteven/beets,mosesfistos1/beetbox,shamangeorge/beets,arabenjamin/beets,drm00/beets,shanemikel/beets,Dishwishy/beets,Dishwishy/beets,beetbox/beets,untitaker/beets,mried/beets,beetbox/beets,PierreRust/beets,imsparsh/beets,parapente/beets,imsparsh/beets,tima/beets,madmouser1/beets