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

Add modules directory to BSUBDIRS.

Add the pxechain module from Jeffery Hutzelman at CMU.
Create new modules directory for non-com32 modules.
Centralize installation, since we have three types of install, and
only one of them was distributed.

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

Cleanup and centralize the Makefile system even more.
Fix a gcc 4.3 incompatibility in memdisk (definition of strlen).

Centralize more (most) of the version number machinery to version.pl.

Clean up the BSUBDIR/ISUBDIR separation further.  Build _bin.c files,
which are an intermediate stage toward building the installers, in the
libinstaller directory, since that directory is used by all the
installers anyway.  That also lets us get bin2c.pl out of the root.

- "make clean" should not clean up things that "make installer" cannot
  regenerate.
- "make installer" should not descend into subdirectories which are
  target only, e.g. com32 and sample.

The Linux platform stuff in com32 is old and bitrotted, and was only
for debugging in the first place.  Just ignore it.

Add support for creating codepage/Unicode mapping tables; this is a
step toward VFAT long filename support.

Begin the process of centralizing configurables.

Improve "make install" and "make netinstall"; add "make
extbootinstall".

The only things we still have in the root is version.h and
version.gen.  As a result, move all the subdirectories later, since
they are common prerequisites.