Introduce public API for domain async job handling

Introduce a new public API that provides a way to get progress
info on currently running jobs on a virDomainpPtr. APIs that
are initially within scope of this idea are

 virDomainMigrate
 virDomainMigrateToURI
 virDomainSave
 virDomainRestore
 virDomainCoreDump

These all take a potentially long time and benefit from monitoring.
The virDomainJobInfo struct allows for various pieces of information
to be reported

 - Percentage completion
 - Time
 - Overall data
 - Guest memory data
 - Guest disk/file data

* include/libvirt/libvirt.h.in: Add virDomainGetJobInfo
* python/generator.py, python/libvirt-override-api.xml,
  python/libvirt-override.c: Override for virDomainGetJobInfo API
* python/typewrappers.c, python/typewrappers.h: Introduce wrapper
  for unsigned long long type

python/typewrappers.c

@@ -48,6 +48,14 @@ libvirt_longlongWrap(long long val)
     return (ret);
 }
 
+PyObject *
+libvirt_ulonglongWrap(unsigned long long val)
+{
+    PyObject *ret;
+    ret = PyLong_FromUnsignedLongLong(val);
+    return (ret);
+}
+
 PyObject *
 libvirt_charPtrWrap(char *str)
 {