Rename internal APis

Rename internal APis

Rename virDomainIsActive to virDomainObjIsActive, and
virInterfaceIsActive to virInterfaceObjIsActive and finally
virNetworkIsActive to virNetworkObjIsActive.

* src/conf/domain_conf.c, src/conf/domain_conf.h,
  src/conf/interface_conf.h, src/conf/network_conf.c,
  src/conf/network_conf.h, src/lxc/lxc_driver.c,
  src/network/bridge_driver.c, src/opennebula/one_driver.c,
  src/openvz/openvz_driver.c, src/qemu/qemu_driver.c,
  src/test/test_driver.c, src/uml/uml_driver.c: Update for
  renamed APIs.