Initially thought it was best to keep the old function around and add a new
one, but this so many ssl_set_xxx() functions are changing anyway...

This is temporary, they will soon be replaced by callbacks.
!!! In this intermediate step security is removed !!!

Initially thought it would be per-connection, but since max_version is in conf
too, and you need to lower that for a fallback connection, the fallback flag
should be in the same place

mbedtls_ssl_set_alpn_protocols
mbedtls_ssl_set_arc4_support
mbedtls_ssl_set_authmode
mbedtls_ssl_set_ciphersuites
mbedtls_ssl_set_ciphersuites_for_version
mbedtls_ssl_set_curves
mbedtls_ssl_set_dbg
mbedtls_ssl_set_dh_param
mbedtls_ssl_set_dh_param_ctx
mbedtls_ssl_set_dtls_anti_replay
mbedtls_ssl_set_dtls_badmac_limit
mbedtls_ssl_set_dtls_cookies
mbedtls_ssl_set_encrypt_then_mac
mbedtls_ssl_set_endpoint
mbedtls_ssl_set_extended_master_secret
mbedtls_ssl_set_handshake_timeout
mbedtls_ssl_legacy_renegotiation
mbedtls_ssl_set_max_version
mbedtls_ssl_set_min_version
mbedtls_ssl_set_psk_cb
mbedtls_ssl_set_renegotiation
mbedtls_ssl_set_renegotiation_enforced
mbedtls_ssl_set_renegotiation_period
mbedtls_ssl_set_session_cache
mbedtls_ssl_set_session_ticket_lifetime
mbedtls_ssl_set_sni
mbedtls_ssl_set_transport
mbedtls_ssl_set_truncated_hmac
mbedtls_ssl_set_verify

A simple series of sed invocations.

This is the first step, purely internal changes. The conf substructure is not
ready to be shared between contexts yet.

For some reason, during the great renaming, some names that should have been
prefixed with MBEDTLS_X509_ have only been prefixed with MBEDTLS_

A simple execution of tmp/invoke-rename.pl

Became unused when removing deprecated ssl_set_own_cert_xxx() functions

Repeatedly allocating a context and setting the key was a waste

Note from future self: actually md_init_ctx will be re-introduced with the
same signature later, and a new function with the additional argument will be
added.