Change all calls to low level digest routines in the library and
applications to use EVP. Add missing calls to HMAC_cleanup() and
don't assume HMAC_CTX can be copied using memcpy().

Note: this is almost identical to the patch submitted to openssl-dev
by Verdon Walker <VWalker@novell.com> except some redundant
EVP_add_digest_()/EVP_cleanup() calls were removed and some changes
made to avoid compiler warnings.