Unexport some conf layers unused outside of libcrypto

Unexport some conf layers unused outside of libcrypto

imodules are called imodules because they contain Information about
modules that have been Initialized. Which one of these two I it is
is anyone's best guess. Why anything outside of libcrypto would ever
possibly care will also remain a mystery.

Remove the old way of adding a conf module, user data, stop allowing
to set a method (it's opaque now, remember?) and drop a couple bits
more from the public api interface.

ok beck jsing