Currently the installation of libmcal installs the *.h files in /usr/local/mcal/include. Should this not be /usr/local/include/mcal? Using the latter would allow programs to include 'mcal/mcal.h' rather than trying to get the include path modified during compile.
It just seems backwards to me to.
Also the tar file that is build for distributing the source should also include the version in the top level directory (i.e. libmcal-0.6 instead of just libmcal).