C code and associated .so for ctype extension

Signed-off-by: Balthazar Rouberol <rouberol.b@gmail.com>
relative link to .so, located in venv site-packages directory

Signed-off-by: Balthazar Rouberol <rouberol.b@gmail.com>
Automatic compilation of haversine.c into libhsine.so at install

Signed-off-by: Balthazar Rouberol <rouberol.b@gmail.com>