ECAL tilt angle is back, calculation of beginning and end of cells is added to ECAL_geo.cpp for PicoCal, to be mimicked in DeCalorimeter and in ECAL_geo of RUN4

rationalized detElements in ECAL_geo.cpp, added rows and cols in XML for shashlik modules, fixed wrong type in reading XML files in function import_module_coordinates_from_xml of ECAL_geo.cpp

modified function to read positions and rotations of modules, now gets info from an XML file and the problem of absolute paths is solved

Rich: Minor additions and cleanup

See merge request !639

ECAL tilt angle is back, calculation of beginning and end of cells is added to ECAL_geo.cpp for PicoCal, to be mimicked in DeCalorimeter and in ECAL_geo of RUN4

rationalized detElements in ECAL_geo.cpp, added rows and cols in XML for shashlik modules, fixed wrong type in reading XML files in function import_module_coordinates_from_xml of ECAL_geo.cpp

modified function to read positions and rotations of modules, now gets info from an XML file and the problem of absolute paths is solved

VPChannelID setters return reference to *this

See merge request !651