AthenaPython: Update CORAL attribute access for python 3.

Update the handling of CORAL attributes to work with both py3 and py2.
Can simplify it now using a pyroot template proxy.

Control/AthenaPython/python/FilePeekerLib.py

@@ -15,22 +15,6 @@ __doc__ = "provide components to peek into pool files"
 import AthenaPython.PyAthena as PyAthena
 StatusCode = PyAthena.StatusCode
 
-# MN/sss: make Coral.AttributeList work in Coral3/ROOT6/gcc5
-from PyCool import coral
-_attribute_methods = dir(coral.Attribute)
-_methnames = ['data<std::__cxx11::basic_string<char> >',
-              'data<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >',
-              'data<std::basic_string<char> >',
-              'data<std::string>']
-for _m in _methnames:
-    if _m in _attribute_methods:
-        _attribute_getdata = _m
-        break
-else:
-    raise Exception("Can't find data method in Attribute")
-def attr_str_data(attr):
-    return getattr(attr, _attribute_getdata) ()
-
 
 ### helper functions ----------------------------------------------------------
 def _import_ROOT():
@@ -245,14 +229,14 @@ class FilePeeker(PyAthena.Alg):
                     spec   = a.specification()
                     a_type = spec.typeName()
                     if a_type.find('string') >= 0:
-                        a_data = attr_str_data(a)
+                        a_data = a.data('string')()
                         try:
                             a_data = eval(a_data,{},{})
                         except Exception:
                             # swallow and keep as a string
                             pass
                     else:
-                        a_data = getattr(a,'data<%s>'%a_type)()
+                        a_data = a.data(a_type)()
                     #msg.info("%s: %s  %s", spec.name(), a_data, type(a_data) )
                     attr_data.append( (spec.name(), a_data) )
                 attrs.append(dict(attr_data))