Prior to this change, the user needed to install inih as a dependency,
either from the distribution repositories, or from source. On some
platforms (notably macOS), inih is not available prepackaged, and must
be installed by the user. This tends to cause needless friction.
This change imports the ini.c and ini.h files from the upstream inih
repository into the X52 source tree. This will allow us to build the
repository on any system with the original set of dependencies, and not
have to force the user to install packages themselves.
