progress/resume for item imports
progress/resume for item imports

In this implementation, progress is only saved at the directory granularity,
just like with album imports. This is the only easy way to make the progress
stuff interoperable between the two styles of import. With duplicate detection
in place, this is not such a big deal.

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