* h/mhparse.h: Move interfaces also used by mhbuildsbr.c here

	* h/mhparse.h: Move interfaces also used by mhbuildsbr.c here
	from mhparse.c.

	* uip/Makefile.in (mhbuild): Build with mhparse.o.

	* uip/mhbuildsbr.c: Drop the duplication of mhparse.c.

	* uip/mhbuild.c, uip/mhlist.c, uip/mhn.c, uip/mhshow.c,
	uip/mhstore.c, uip/mhtest.c: Drop check swdeclaration, which is
	now in mhparse.h.

	* uip/mhparse.c: Move some declarations to mhparse.h, and remove
	'static' from the definitions here.
	(get_ctinfo): Take magic mhbuild support from mhbuildsbr.c's copy,
	and adapt callers.
	(incl_name_value, extract_name_value): Move from mhbuildsbr.c to
	support get_ctinfo change).
	(get_content, open7Bit): Add Content-Disposition support, added to
	mhbuildsbr.c's copy in mhbuildsbr.c r1.12 (PatchSet 549).
	(InitText): Default to CHARSET_UNSPECIFIED instead of "US-ASCII",
	as mhbuildsbr.c's copy did.  Explain termproc.
	(openBase64, openQuoted, open7Bit): Fix comment from r1.5:
	suffixes, not prefixes.
	(openMail): Explain showproc.

	* test/tests/mhshow/test-cte-binary: Add test for
	Content-Transfer-Encoding: binary (Debian #136976).

	* test/tests/mhbuild/test-forw: Add an mhbuild test, testing forw
	with and without RFC-934 mode.  More mhbuild tests would be nice.