[libvirt] stateless drivers and stored lists of virDomainObjs

Hello, vmware, openvz and parallels driver, which was written with first two ones as an example, get list of domains in virConnectOpen and then use it for lookups and even for listing sometimes. This is not correct, because you can make several connections to the same driver and changes, made in one connection will not be visible to other. And you can also create or destroy domains using native tools. So I think keeping list of domains in a stateless driver is a bad idea - you should update this list each time when user requests some info. It's better to retrieve needed data only when it requested, like in xenapi driver. I asked this because I want to continue developing parallels driver and it'= s not so hard to change it now, so it should be fixed before adding any new code there. Maybe vmware and openvz drivers should be also fixed. -- Dmitry Guryanov