Clean up Crypt::SSLeay::MainContext

I don't even know why there was a home-made import method in that package.
Also got rid of a couple of package globals.
Remove unnecessary buffer copying in SSL_CTX_new
Inherit from IO::Socket::IP if available

Test failure was due to change in error string fix that.
Also, Socket provides a $CRLF constant. Use that instead of using a package
global variable.
Clean up info callback used when debugging is enabled
Clean up SSL_new
Use IO::Socket::IP if available, and clean up