Allow line buffer to accumulate multiple lines, with buffered_line()
returning each freshly-completed line as it is encountered.  This
allows buffered lines to be subsequently processed as a group.

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resources has been revoked by the registrant of the domain.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>

that switches from line-oriented to byte-oriented partway through, such as
HTTP.