Extend and cleanup the VMX to domain XML mapping. Add the domain XML to
VMX mapping functions.

* src/esx/esx_driver.c: add esxDomainXMLToNative()
* src/esx/esx_vmx.[ch]: add esxVMX_SCSIDiskNameToControllerAndID(),
  esxVMX_IDEDiskNameToControllerAndID(), esxVMX_FloppyDiskNameToController(),
  esxVMX_GatherSCSIControllers(), add basic handling for the VMX guestOS entry
  to distinguish between i686 and x86_64, make SCSI virtualDev VMX entry
  optional as it should be, map the VMX networkName entry to the domain XML
  interface bridge name, add basic mapping for serial devices in pipe mode,
  add several esxVMX_Format*() functions

Add the virStrncpy function, which takes a dst string, source string,
the number of bytes to copy and the number of bytes available in the
dest string.  If the source string is too large to fit into the
destination string, including the \0 byte, then no data is copied and
the function returns NULL.  Otherwise, this function copies n bytes
from source into dst, including the \0, and returns a pointer to the
dst string.  This function is intended to replace all unsafe uses
of strncpy in the code base, since strncpy does *not* guarantee that
the buffer terminates with a \0.
Signed-off-by: NChris Lalancette <clalance@redhat.com>

* src/esx/esx_vmx.c: add it to the list of accepted devices when
  parsing the Ethernet section.

* src/esx/esx_vmx.c: add an extra type of addressType beside 'static'
  and 'generated', 'vpx' indicates that the MAC address was generated
  by a vCenter.

While trying to remove uses of unsafe strncpy in the tree, I came
across a couple of usages in the ESX driver.  To my eyes, the snprintf
replacements do the same thing in less code, and are also safer.
Signed-off-by: NChris Lalancette <clalance@redhat.com>
Tested-by: NMattias Bolte <matthias.bolte@googlemail.com>

* src/esx/esx_driver.c src/esx/esx_vi.[ch] src/esx/esx_vmx.[ch]:
  adds version checking for GSX 2.0, allows to pass a specific port
  for the connection and also add a new specific gsx scheme for
  easier connections to GSX hosts

* src/esx/esx_driver.c src/esx/esx_vi.c src/esx/esx_vi.h
  src/esx/esx_vmx.c src/esx/esx_vmx.h: extend the VI API version checks
  to accept version 4.0 and takes care of the virtualHW.version change
  from 4 to 7.

* src/esx/esx_*.[ch]: the driver, uses a remote minimal SOAP client
  to talk to the VI services on ESX nodes.
* configure.in include/libvirt/virterror.h src/Makefile.am src/driver.h
  src/libvirt.c src/virterror.c: glue in the new driver