Improve the appearance of the "config" user interface by ensuring that
settings appear in some kind of logical order.

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

Expose a function setting_applies() to allow a caller to determine
whether or not a particular setting is applicable to a particular
settings block.

Restrict DHCP-backed settings blocks to accepting only DHCP-based
settings.

Restrict network device settings blocks to accepting only DHCP-based
settings and network device-specific settings such as "mac".

Inspired-by: Glenn Brown <glenn@myri.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Pass the settings block name as a parameter to register_settings(),
rather than defining it with settings_init() (and then possibly
changing it by directly manipulating settings->name).

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

Access to the gpxe.org and etherboot.org domains and associated
resources has been revoked by the registrant of the domain.  Work
around this problem by renaming project from gPXE to iPXE, and
updating URLs to match.

Also update README, LOG and COPYRIGHTS to remove obsolete information.

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

This provides a mechanism for using arbitrarily-named variables within
gPXE, using the existing syntax for settings.

Add FILE_LICENCE declarations to almost all files that make up the
various standard builds of gPXE.

Add SMBIOS asset tag as a named setting.

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

EFI provides a copy of the SMBIOS table accessible via the EFI system
table, which we should use instead of manually scanning through the
F000:0000 segment.