• Add and fix functions needed to properly implement client
  side session reuse for TLS 1.3 with using
  CTX_sess_set_new_cb. Newly exposed functions:
  SSL_SESSION_dup and SSL_SESSION_up_ref.
  Fixed functions: i2d_SSL_SESSION and d2i_SSL_SESSION.
  Thanks to Steffen Ullrich.
  
• Add functions functions to allow reading multiple pems from
  file and creating untrusted chain: These functions allow you
  to:
  
  • Read in a PEM file with multiple certificates as a
    STACK_OF(X509_INFO)
    
  • Determine the size of the STACK_OF(X509_INFO) and value at
    an index, which allows you to loop over the stack.
    
  • Retrieve the X509 structure from each X509_INFO structure
    in the stack.
    Then you can create a new STACK_OF(X509) and push the X509
    structures onto the new stack. You can then pass this
    STACK_OF(X509) to X509_STORE_CTX_init which will allow you
    to add additional untrusted certificates to the chain for
    verification. Exposed functions are:
    PEM_X509_INFO_read_bio
    sk_X509_INFO_num
    sk_X509_INFO_value
    sk_X509_INFO_free
    sk_X509_new_null
    sk_X509_free
    sk_X509_push
    New function implemented by Net::SSLeay:
    P_X509_INFO_get_x509
    Thanks to Marc Reisner.
    
• Add functions and constants that are necessary to verify a
  certificate using a hash directory outside of an SSL/TLS
  connection. Newly exposed functions:
  X509_STORE_CTX_init
  X509_STORE_CTX_free
  X509_STORE_new
  X509_STORE_free
  X509_STORE_add_lookup
  X509_LOOKUP_hash_dir
  X509_LOOKUP_add_dir
  Newly exposed constants:
  X509_FILETYPE_ASN1
  X509_FILETYPE_DEFAULT
  X509_FILETYPE_PEM
  Thanks to Marc Reisner.
  
• Declare n_a in ssleay_set_psk_client_callback_invoke and
  ssleay_ctx_set_psk_client_callback_invoke to avoid a compilation
  error with Perl versions below 5.8.8. Fixes RT#128030. Thanks to
  Graham Ollis for the report.
  
• Add X509_get0_serialNumber. Thanks to Marc Reisner.
  
• Enable Travis CI for LibreSSL 2.2.1, 2.7.5, 2.8.3 and 2.9.0
  on Perl 5.20 and more recent.
  
• Expose the following functions for curve and group selection:
  
  • CTX_set_ecdh_auto, set_ecdh_auto
    
  • CTX_set1_curves_list, set1_curves_list
    
  • CTX_set1_groups_list, set1_groups_list
    Thanks to Steffen Ullrich.