webservice to reference ref_points is ready

first steps of add_reference.php webservice : input validation/sanitization and RefPoint class

small fixes arround site_point::get_all() usage

moved all_points webservice to use methods from site_point

make use of constants

linked the map points to panorama visualization

FIXUP

now displays the circles with the same color as on the pano (sortof...)

Added a display of all the ref_points on the map.