Newer versions of OpenSSL have engine mechanism which
allows to use alternate (i.e. hardware) implementation
of cryptoalgorithms. Most SSL applications such as
apache/mod_ssl or stunnel already have support for
engines (via config file). It is desirable to allow
tcltls applications be engine-aware too.
Simplest way for to support engines is to read default
openssl configuration file via OPENSSL_config function,
but more flexible is to specify engine id and options
via special tcl command.