Updated/fixed changelog
Fixed typo and updated README
Warn if SSLv3 is disabled in OpenSSL
cleanup whitespace
Facilitate Git tags to get version information.

Inject version number at compile time via `-DVERSION`.

Also, don't differentiate between `program_version` and `xml_version`.
XML: Add "sslmethod" attribute to heartbleed element.

There may or may be not a custom OpenSSL build out there,
which is only vulnerable to Heartbleed via TLSv1.0, but not
via 1.1 or 1.2. Since the XML did not include this information,
there was no chance to automatically discover this
strangeness.

Also: simplified `SSL_METHOD`→string conversion.
add a few more `ifndef OPENSSL_NO_SSL3` and enable more warnings
gitignore custom OpenSSL build
add header file

- unclutter code
- externalize function prototypes and definitions
allow statically linking of OpenSSL
Possible fix for #15
Print verbose output if STARTTLS SMTP fails