global: don't cast NULL to void * NULL is guaranteed to be a void * thanks to dd6043c05e32a8e8db1233ed711a2c74d1477a89.
Updated copyright notices to include the year 2018.
lib-smtp: server: Moved ssl_start argument from smtp_server_connection_start() to smtp_server_connection_create(). This frees smtp_server_connection_start() for general use.
lib-smtp: fix uoff_t vs. size_t confusion
lib-smtp: Created test-smtp-payload, which tests client<->server payload exchange.