patch from Stéphane Bidoul for better per context error message APIs

* xmlreader.c python/drv_libxml2.py python/generator.py
  python/libxml.c python/libxml.py python/libxml_wrap.h
  python/types.c: patch from Stéphane Bidoul for better per
  context error message APIs
* python/tests/ctxterror.py python/tests/readererr.py:
  update of the tests
Daniel
diff --git a/python/tests/readererr.py b/python/tests/readererr.py
index abbbba5..dbdeb47 100644
--- a/python/tests/readererr.py
+++ b/python/tests/readererr.py
@@ -13,14 +13,14 @@
 --> (4) test1:1:Opening and ending tag mismatch: c and a
 """
 err=""
-def myErrorHandler(arg,msg,line,col,URI,severity):
+def myErrorHandler(arg,msg,severity,locator):
     global err
-    err = err + "%s (%d) %s:%d:%s" % (arg,severity,URI,line,msg)
+    err = err + "%s (%d) %s:%d:%s" % (arg,severity,locator.BaseURI(),locator.LineNumber(),msg)
 
 f = StringIO.StringIO("""<a xmlns="foo"><b b1="b1"/><c>content of c</a>""")
 input = libxml2.inputBuffer(f)
 reader = input.newTextReader("test1")
-reader.setErrorHandler(myErrorHandler,"-->")
+reader.SetErrorHandler(myErrorHandler,"-->")
 while reader.Read() == 1:
     pass
 
@@ -30,9 +30,9 @@
     print "expected %s" %(expect)
     sys.exit(1)
 
-reader.setErrorHandler(None,None)
-if reader.getErrorHandler() != (None,None):
-    print "getErrorHandler failed"
+reader.SetErrorHandler(None,None)
+if reader.GetErrorHandler() != (None,None):
+    print "GetErrorHandler failed"
     sys.exit(1)
 
 #