...There also also doesn't exist a library for common functionality, such as error reporting/logging, string functions, configuration management (reading config files), etc...
The programmer working in C doesn't have anything analogous to the Boost C++ library. The extended C library is intended to make some headway into providing this functionality. To ensure unrestricted usage the libxc project is provided under the very permissive BSD license. If you need a different license then please send me a request (lelanthran at gmail) and I'll do my best to satisfy your request.
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