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

The userptr_t is now the fundamental type that gets used for conversions.
For example, virt_to_phys() is implemented in terms of virt_to_user() and
user_to_phys().

outside of librm.S.

advantage of the fact that we have to have a permanently-resident block
in base memory.

initialise_via_librm.

call it initialise() and place it in main.c.  :)

of librm.