Licensing and Contributions
As you have seen, some of these tools are available with full source code. They are licensed under the LGPL (Lesser General Public License, www.gnu.org/copyleft/lesser.html), which means you can freely use and redistribute them in any way, including making modifications, while the author retains the original copyright. The LGPL doesn't allow you to close-source your extensions, but you can use this library code within programs you sell, regardless of the source code availability. If you extend these tools by fixing bugs or adding new features, I ask you to send your updates to me so I can further distribute the enhancements and we can avoid forking the code into too many versions. The license does not require you to do so, though.