forward declarations

Any error in parsing or validation of version string will result in Parse_error exception being thrown.

Compare Version_data to another using semantic versioning 2.0.0 rules.

Parse string into Version_data structure according to semantic versioning 2.0.0 rules.

Concrete version class that binds all semver 2.0.0 functionality together.

The original bsdiff.c source code (http://www.daemonology.net/bsdiff/) is distributed under the following license: Copyright 2003-2005 Colin