Improved `make dist` so that it distributes all files versioned by Git
Added back the old man page that somehow got deleted during development
Updated `Doxyfile` to Doxygen version 1.8.7 and included a main page for the documentation
Bumped to v2.0.7, updating some project files.

* Cleaned the `BUGS` file, pointing to the GitHub issue tracker
* Made the `NEWS` file point to my latest blog posts on nsnake
* Commented on the TODO file