cli: --graphics: Add zlib.compression=

This maps --graphics zlib.compression=auto to the XML:

  <graphics>
    <zlib compression='auto'/>
  </graphics>

tests/cli-test-xml/compare/virt-install-many-devices.xml

@@ -369,6 +369,7 @@
       <clipboard copypaste="yes"/>
       <mouse mode="client"/>
       <filetransfer enable="yes"/>
+      <zlib compression="always"/>
     </graphics>
     <graphics type="spice" tlsPort="6000" passwd="testpass" passwdValidTo="2010-04-09T15:51:01" defaultMode="insecure">
       <gl enable="yes" rendernode="/dev/dri/by-path/pci-0000:00:02.0-render"/>

tests/clitest.py

@@ -551,7 +551,7 @@ source.reservations.managed=no,source.reservations.source.type=unix,source.reser
 --graphics spice,keymap=none
 --graphics vnc,port=5950,listen=1.2.3.4,keymap=ja,password=foo
 --graphics spice,port=5950,tlsport=5950,listen=1.2.3.4,keymap=ja
---graphics spice,image_compression=glz,streaming_mode=filter,clipboard_copypaste=yes,mouse_mode=client,filetransfer_enable=on
+--graphics spice,image_compression=glz,streaming_mode=filter,clipboard_copypaste=yes,mouse_mode=client,filetransfer_enable=on,zlib.compression=always
 --graphics spice,gl=yes,listen=socket,image.compression=glz,streaming.mode=filter,clipboard.copypaste=yes,mouse.mode=client,filetransfer.enable=on,tlsPort=6000,passwd=testpass,passwdValidTo=2010-04-09T15:51:00,passwordValidTo=2010-04-09T15:51:01,defaultMode=insecure
 --graphics spice,gl=yes,listen=none
 --graphics spice,gl.enable=yes,listen=none,rendernode=/dev/dri/foo,gl.rendernode=/dev/dri/foo2

virtinst/cli.py

@@ -3205,6 +3205,7 @@ class ParserGraphics(VirtCLIParser):
         cls.add_arg("mouse.mode", "mouse_mode")
         cls.add_arg("filetransfer.enable", "filetransfer_enable",
                     is_onoff=True)
+        cls.add_arg("zlib.compression", "zlib_compression")
 
         cls.add_arg("gl.enable", "gl", is_onoff=True)
         cls.add_arg("gl.rendernode", "rendernode")

virtinst/devices/graphics.py

@@ -193,6 +193,7 @@ class DeviceGraphics(Device):
     filetransfer_enable = XMLProperty("./filetransfer/@enable", is_yesno=True)
     gl = XMLProperty("./gl/@enable", is_yesno=True)
     rendernode = XMLProperty("./gl/@rendernode")
+    zlib_compression = XMLProperty("./zlib/@compression")
 
 
     ##################