Relicense files authored by Dan Lynch while working as an employee of
Fen Systems Ltd., with permission from Fen Systems Ltd.

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.

- reimplemented cleaner wgetnstr
- fixed wdelch for use with _wcursback

- corrected minor algo errors in primitives
- added doxygen @file header

library use later on
- some small mods to existing functions