The introduction of the v3 migration protocol, along with
support for migration cookies, will significantly expand
the size of the migration code. Move it all to a separate
file to make it more manageable

The functions are not moved 100%. The API entry points
remain in the main QEMU driver, but once the public
virDomainPtr is resolved to the internal virDomainObjPtr,
all following code is moved.

This will allow the new v3 API entry points to call into the
same shared internal migration functions

* src/qemu/qemu_domain.c, src/qemu/qemu_domain.h: Add
  qemuDomainFormatXML helper method
* src/qemu/qemu_driver.c: Remove all migration code
* src/qemu/qemu_migration.c, src/qemu/qemu_migration.h: Add
  all migration code.

Move the qemudStartVMDaemon and qemudShutdownVMDaemon
methods into a separate file, renaming them to
qemuProcessStart, qemuProcessStop. All helper methods
called by these are also moved & renamed to match

* src/Makefile.am: Add qemu_process.c/.h
* src/qemu/qemu_command.c: Add qemuDomainAssignPCIAddresses
* src/qemu/qemu_command.h: Add VNC port min/max
* src/qemu/qemu_domain.c, src/qemu/qemu_domain.h: Add
  domain event queue helpers
* src/qemu/qemu_driver.c, src/qemu/qemu_driver.h: Remove
  all QEMU process startup/shutdown functions
* src/qemu/qemu_process.c, src/qemu/qemu_process.h: Add
  all QEMU process startup/shutdown functions

* src/conf/domain_conf.h (virDomainChrDeviceType): Drop monitor.
* src/conf/domain_conf.c (virDomainChrDevice)
(virDomainChrDefParseTargetXML, virDomainChrDefFormat): Drop
monitor support.
* src/qemu/qemu_command.h (qemuBuildCommandLine): Alter signature.
* src/qemu/qemu_monitor.h (qemuMonitorOpen): Likewise.
* src/qemu/qemu_domain.h (_qemuDomainObjPrivate): Change type of
monConfig.
* src/qemu/qemu_domain.c (qemuDomainObjPrivateFree)
(qemuDomainObjPrivateXMLFormat, qemuDomainObjPrivateXMLParse):
Adjust to type change.
* src/qemu/qemu_command.c (qemuBuildCommandLine): Likewise.
* src/qemu/qemu_driver.c (qemuPrepareMonitorChr)
(qemudStartVMDaemon, qemuDomainXMLToNative, qemuConnectMonitor)
(qemudShutdownVMDaemon): Likewise.
* src/qemu/qemu_hotplug.c (qemuDomainAttachNetDevice): Likewise.
* src/qemu/qemu_monitor.c (qemuMonitorOpen): Likewise.
* tests/qemuxml2argvtest.c (testCompareXMLToArgvFiles): Likewise.

To allow the APIs to be used from separate files, move the domain
lock / job helper code into qemu_domain.c

* src/qemu/qemu_domain.c, src/qemu/qemu_domain.h: Add domain lock
  / job code
* src/qemu/qemu_driver.c: Remove domain lock / job code

Move the code for handling the QEMU virDomainObjPtr private
data, and custom XML namespace into a separate file

* src/qemu/qemu_domain.c, src/qemu/qemu_domain.h: New file
  for private data & namespace code
* src/qemu/qemu_driver.c, src/qemu/qemu_driver.h: Remove
  private data & namespace code
* src/qemu/qemu_driver.h, src/qemu/qemu_command.h: Update
  includes
* src/Makefile.am: Add src/qemu/qemu_domain.c