Semantic versioning

[langston-barrett]

We should decide and document what the public API of cclyzer++ is. It probably contains at least the filenames that are ouput by the non-debug .project files, and might include the C++ API for consuming those files.

After documenting this, we should commit to semantic versioning with respect to it, since this is a widely-used versioning scheme that will help consumers understand and effectively use different versions of cclyzer++.