[build] Rename gPXE to iPXE

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resources has been revoked by the registrant of the domain.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

src/net/80211/rc80211.c

@@ -1,5 +1,5 @@
 /*
- * Simple 802.11 rate-control algorithm for gPXE.
+ * Simple 802.11 rate-control algorithm for iPXE.
  *
  * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
  *
@@ -21,7 +21,7 @@
 FILE_LICENCE ( GPL2_OR_LATER );
 
 #include <stdlib.h>
-#include <gpxe/net80211.h>
+#include <ipxe/net80211.h>
 
 /**
  * @file
@@ -69,11 +69,11 @@ FILE_LICENCE ( GPL2_OR_LATER );
  * below some threshold, and try increasing our rate when the goodness
  * is very high.
  *
- * This system is optimized for gPXE's style of usage. Because normal
+ * This system is optimized for iPXE's style of usage. Because normal
  * operation always involves receiving something, we'll make our way
  * to the best rate pretty quickly. We tend to follow the lead of the
  * sending AP in choosing rates, but we won't use rates for long that
- * don't work well for us in transmission. We assume gPXE won't be
+ * don't work well for us in transmission. We assume iPXE won't be
  * running for long enough that rate patterns will change much, so we
  * don't have to keep time counters or the like.  And if this doesn't
  * work well in practice there are many ways it could be tweaked.