[Nmh-workers] imap support, and portability

[Lyndon Nerenberg (VE6BBM/VE7TFX)]

Fuse is a major step forward for UNIX-like systems.  But Fuse can
never be as portable as a conforming POSIX application.  MH has always
been able to compile on anything even remotely resembling UNIX.  Tying
it to a very implementation-specific API like this would negate nearly
30 years of portability.

The same goal can be achieved through a 'helper' application that
proxies between the local MH and the remote IMAP store. Everything
you need is in POSIX (i.e. the socket layer). It's more work to write,
but it will build on a lot more platforms.

--lyndon