Update README and file-level comments after the NCP/IPX source split and
renames.
Document the current layering: ncpapi.c/ncpapi.h contain the ncpXX_YY_*
protocol API wrappers, ncpcall.c contains low-level requester/transport
helpers, ncp.asm/ncp.h provide INT 21h and Client32 requester entry points, and
ipx.asm/ipx.h provide IPX and far-memory assembly glue.
Also remove stale c32ncp/kern_wasm/kern.h planning references and update the
license section to mention the root-level COPYING file.
No behavior change.
Finish the ncpcall.asm/ncpcall.h to ncp.asm/ncp.h rename.
Update the Open Watcom build, object names, include directives, header guard,
README references and file-level dependency comments to use the shorter ncp
naming. The split remains the same: ncp.asm/ncp.h provide the low-level INT 21h
and Client32 requester entry points, ncpcall.c contains requester transport
helpers, and ncpapi.c contains the ncpXX_YY_* protocol API wrappers.
No behavior change.
