Add setter to Container to allow for delayed adding of children (and make constructing drawable trees more elegant).
Add setter to Container to allow for delayed adding of children (and make constructing drawable trees more elegant).

Nabile-Rahmani/osu-framework,ZLima12/osu-framework,NeoAdonis/osu-framework,naoey/osu-framework,paparony03/osu-framework,default0/osu-framework,naoey/osu-framework,peppy/osu-framework,RedNesto/osu-framework,paparony03/osu-framework,ppy/osu-framework,ppy/osu-framework,smoogipooo/osu-framework,DrabWeb/osu-framework,Nabile-Rahmani/osu-framework,smoogipooo/osu-framework,peppy/osu-framework,ZLima12/osu-framework,EVAST9919/osu-framework,default0/osu-framework,Tom94/osu-framework,NeoAdonis/osu-framework,EVAST9919/osu-framework,RedNesto/osu-framework,EVAST9919/osu-framework,Tom94/osu-framework,DrabWeb/osu-framework,ppy/osu-framework,EVAST9919/osu-framework,DrabWeb/osu-framework,peppy/osu-framework