Avoid using UINT16 and similar typedefs, which are non-standard in the
iPXE codebase and generate conflicts when trying to include any of the
EFI headers.

Also fix trailing whitespace in the affected files, to prevent
complaints from git.

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

Fixes in comments and debug messages:

  existance -> existence
  unecessary -> unnecessary
  occured -> occurred
  decriptor -> descriptor
  neccessary -> necessary
  addres, adress -> address
  initilize -> initialize
  sucessfully -> successfully
  paramter -> parameter
  acess -> access
  upto -> up to
  likelyhood ->likelihood
  thru -> through
  substracting -> subtracting
  lenght -> length
  isnt -> isn't
  interupt -> interrupt
  publically -> publicly (this one was not wrong, but unusual)
  recieve -> receive
  accessable -> accessible
  seperately -> separately
  pacet -> packet
  controled -> controlled
  dectect -> detect
  indicies -> indices
  extremly -> extremely
  boundry -> boundary
  usefull -> useful
  unuseable -> unusable
  auxilliary -> auxiliary
  embeded -> embedded
  enviroment -> environment
  sturcture -> structure
  complier -> compiler
  constructes -> constructs
  supress -> suppress
  intruduced -> introduced
  compatability -> compatibility
  verfication -> verification
  ths -> the
  reponse -> response

Fixes in local variable names:

  retreive -> retrieve

Most of these fixes were made using codespell.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

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