These include files export the interface of the library.

They are specified on the LIB_HDRS line in the src/$ARCH/Makefile.

They are ignored by CVS (see .cvsignore) because they are
installed by the Makefile in the src directory.

The Makefile in the src directory also creates the softlink
from csv to "."  -- this allows user programs to specify
include lines like this:
   #include <csv/csv.h>
This prevents confusion in case there is another csv.h header
file in the -I include path.

