Re: Introducing --gc:arc

[filcuc]

@Araq given that it seems a breaking change what should be done for those 
maintaining any nim package? Is there a way to support both arc and default nim 
gc or is it a drop in replacement? Or should we add a new branch for nim 
version 1.XXXX and land changes there? I'm asking because nimqml uses 
finalizers for releasing unmanaged objects but a the same time I would like to 
offer arc support to community