cleanup_hardware is not needed in core/runkernel.inc: cleanup_hardware
is already invoked from replace_bootstrap.  Furthermore,
cleanup_hardware is defined to preserve all registers, so there is no
need to push/pop ax around it.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

As we're starting to rely more and more on a modified hardware state,
it is really important to clean up on all exit paths.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Fix a set of bogus calls to writestr_early instead of writestr.

Mechanically rename the writestr functions:

	writestr   -> writestr_early
	cwritestr  -> writestr

... to reflect which function is more appropriate to call in normal
circumstances.

Move source files out of the root directory; the root is a mess and
has become virtually unmaintainable.  The Syslinux core now lives in
core/; the Linux and generic utilities has moved into utils/, and
copybs.com has moved into dos/; it had to go somewhere, and it seemed
as good a place as any.