prepare release of 0.21 beta 1
prepare release of 0.21 beta 1

fabianrost84/cython,encukou/cython,dahebolangkuan/cython,madjar/cython,achernet/cython,marscher/cython,marscher/cython,hhsprings/cython,scoder/cython,ABcDexter/cython,acrispin/cython,hickford/cython,hhsprings/cython,slonik-az/cython,fperez/cython,fabianrost84/cython,c-blake/cython,scoder/cython,ABcDexter/cython,achernet/cython,slonik-az/cython,ABcDexter/cython,ChristopherHogan/cython,andreasvc/cython,fabianrost84/cython,madjar/cython,mrGeen/cython,roxyboy/cython,acrispin/cython,fabianrost84/cython,marscher/cython,slonik-az/cython,mcanthony/cython,andreasvc/cython,madjar/cython,slonik-az/cython,ChristopherHogan/cython,hickford/cython,hickford/cython,dahebolangkuan/cython,acrispin/cython,fabianrost84/cython,c-blake/cython,cython/cython,da-woods/cython,JelleZijlstra/cython,da-woods/cython,encukou/cython,cython/cython,JelleZijlstra/cython,JelleZijlstra/cython,fperez/cython,encukou/cython,mcanthony/cython,hickford/cython,slonik-az/cython,hhsprings/cython,encukou/cython,scoder/cython,mcanthony/cython,ChristopherHogan/cython,achernet/cython,fperez/cython,roxyboy/cython,mrGeen/cython,dahebolangkuan/cython,c-blake/cython,c-blake/cython,acrispin/cython,acrispin/cython,dahebolangkuan/cython,roxyboy/cython,achernet/cython,ABcDexter/cython,ABcDexter/cython,marscher/cython,mcanthony/cython,roxyboy/cython,da-woods/cython,marscher/cython,scoder/cython,mrGeen/cython,mrGeen/cython,JelleZijlstra/cython,encukou/cython,madjar/cython,da-woods/cython,andreasvc/cython,achernet/cython,hhsprings/cython,cython/cython,hickford/cython,andreasvc/cython,madjar/cython,hhsprings/cython,mrGeen/cython,andreasvc/cython,cython/cython,c-blake/cython,mcanthony/cython,JelleZijlstra/cython,roxyboy/cython,fperez/cython,dahebolangkuan/cython,fperez/cython