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

monojob_wait() was holding a reference to the completed job, meaning that
various objects would not be freed until the next job was plugged in to
the monojob interface.

The EFI timer runs at one tick per second, so using ">" rather than ">="
results in a two-second gap between dots.

We now have two implementations for the timer API: one using the
time-of-day counter at 40:70 and one using RDTSC.  Both make use of
timer2_udelay().

Print one dot per second while waiting in monojob.c (e.g. for DHCP,
for file downloads, etc.), to inform user that the system has not
locked up.

Patch contributed by Andrew Schran <aschran@google.com>, minor
modification by me.