merlinfvr

@dmacvicar would you accept a PR for this issue? Being able to resize volumes non-destructively would be great. Libvirt already supports this via [virStorageVolResize](https://libvirt.org/html/libvirt-libvirt-storage.html#virStorageVolResize) and [virDomainBlockResize](https://libvirt.org/html/libvirt-libvirt-domain.html#virDomainBlockResize). It seems the former...