Stop using ssl{_ctx,}_security() outside of ssl_seclevel.c

Stop using ssl{_ctx,}_security() outside of ssl_seclevel.c

The API is ugly and we can easily abstract it away. The SSL_SECOP_* stuff
is now confined into ssl_seclevel.c and the rest of the library can make
use of the more straightforward wrappers, which makes it a lot easier on
the eyes.

ok beck jsing