efi_file_install() and efi_download_install() are both used to install
onto existing handles.  There is therefore no need to allow for each
of their calls to InstallMultipleProtocolInterfaces() to create a new
handle.

By passing the handle directly (rather than a pointer to the handle),
we avoid potential confusion (and erroneous debug message colours).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Expose iPXE's images as a UEFI file system, allowing the booted image
to access all images downloaded by iPXE.

This functionality is complementary to the custom iPXE download
protocol.  The iPXE download protocol allows a booted image to utilise
iPXE to download arbitrary URIs, but requires the booted image to
specifically support the custom iPXE download protocol.  The new
functionality limits the booted image to accessing only files that
were already downloaded by iPXE (e.g. as part of a script), but can
work with any generic UEFI image (e.g. the UEFI shell).  Both
protocols are provided simultaneously, and are attached to the SNP
device handle.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

The script include/ipxe/efi/import.pl relies on a particular format
for the #include guard in order to detect EFI headers that are not
imported.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

iPXE exposes some extended capabilities via the PXE FILE API to allow
NBPs such as pxelinux to use protocols other than TFTP.  Provide an
equivalent interface as a UEFI protocol so that EFI binaries may also
take advantage of iPXE's extended capabilities.

This can be used with a patched version of elilo, for example:

  http://comments.gmane.org/gmane.comp.boot-loaders.elilo.general/147

Signed-off-by: Michael Brown <mcb30@ipxe.org>