All vbox objects are child objects from the nsISupports in vbox's
C++ API version. Since the CAPI is generated from the C++ API, I
kept their relationship here, by the definitations below:

typedef struct nsISupports nsISupports;
typedef nsISupports IVirtualBox;
typedef nsISupports ISession;
and so on...

So, when calling the API from nsISupports, we don't need to do
typecasting, and things work still work well.

Introduce vbox_uniformed_api to deal with version conflicts. Use
vbox_install_api to register the currect vboxUniformedAPI with
vbox version.

vboxConnectOpen has been rewritten.

Martin Kletzander pointed out in email that my commit 2a193f64
introduced a crash in networkCreateInterfacePool() during startup of
any network that doesn't have a <pf> subelement of its <forward>
element. He also supplied a patch.

 http://www.redhat.com/archives/libvir-list/2014-August/msg00655.html

I expanded on that patch by cleaning up now-extraneous checks in the
callers of networkCreateInterfacePool().

Fortunately the offending patch hasn't been in any release, and hasn't
been (to my knowledge) backported to any other branch.

Handle formating of VIF config in a new function xenFormatXMVif().
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>

introduce functions
  xenFormatXMSound
  xenFormatXMInputDevs(virConfPtr conf,....);
which formats peripheral device config instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>

introduce function
   xenFormatXMVfb(virConfPtr conf,.........);
which formats Vfb config instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>

introduce functions
   xenFormatXMEmulator(virConfPtr conf,........);
   xenFormatXMCDROM(virConfPtr conf, .......);
   xenFormatXMOS(virConfPtr conf,........);
which formats OS and associated config instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

introduce functions
  xenFormatXMCPUAllocation(virConfPtr conf, ......);
  xenFormatXMCPUFeatures(virConfPtr conf, ......);
which formats CPU allocation and features config
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

introduce function
  xenFormatXMDisks(virConfPtr conf,.........);
which formats domain disks config instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

introduce function
   xenFormatXMCharDev(virConfPtr conf,........);
which formats Char devices config instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

introduce function
   xenFormatXMEventActions(virConfPtr conf,.........);
which formats event actions instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>

introduce function
  xenFormatXMTimeOffset(virConfPtr conf,........);
which formats time config instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

introduce function
   xenFormatXMMem(virConfPtr conf,...........);
which parses memory config instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>

introduce function
  xenFormatXMGeneralMeta(virConfPtr conf,......);
which parses uuid and name instead
Signed-off-by: NKiarie Kahurani <davidkiarie4@gmail.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

The correct vlanid range is 0~4095.

After merging this patch, we can not validate a interface xml with vlanid >= 4096.
[root@localhost ~]# cat vlan.xml
<interface type='vlan' name='eno1.4096'>
   <start mode='onboot'/>
   <protocol family='ipv4'>
    <dhcp/>
   </protocol>
   <vlan tag='4096'>
     <interface name='eno1'/>
   </vlan>
</interface>
[root@localhost ~]# virt-xml-validate vlan.xml
vlan.xml:1: element interface: Relax-NG validity error : Invalid sequence in interleave
vlan.xml:6: element vlan: Relax-NG validity error : Element interface failed to validate content
vlan.xml:6: element vlan: Relax-NG validity error : Element vlan failed to validate attributes
vlan.xml fails to validate
[root@localhost ~]#

Here is a ip command help on this.
[root@localhost /]# ip link add link eno1 name eno1.90 type vlan help
Usage: ... vlan [ protocol VLANPROTO ] id VLANID                [ FLAG-LIST ]
                [ ingress-qos-map QOS-MAP ] [ egress-qos-map QOS-MAP ]

VLANPROTO: [ 802.1Q / 802.1ad ]
VLANID := 0-4095
FLAG-LIST := [ FLAG-LIST ] FLAG
FLAG := [ reorder_hdr { on | off } ] [ gvrp { on | off } ] [ mvrp { on | off } ]
        [ loose_binding { on | off } ]
QOS-MAP := [ QOS-MAP ] QOS-MAPPING
QOS-MAPPING := FROM:TO