applied patch from Markus Keim fixing a problem with I/O callback

* xmlIO.c: applied patch from Markus Keim fixing a problem
  with I/O callback registration.
* include/libxml/xmlerror.h: fixed #122994 comment numbering
  for xmlParserErrors
Daniel
diff --git a/include/libxml/xmlerror.h b/include/libxml/xmlerror.h
index fbccf82..9e1a16d 100644
--- a/include/libxml/xmlerror.h
+++ b/include/libxml/xmlerror.h
@@ -67,37 +67,37 @@
     
     XML_ERR_COMMENT_NOT_FINISHED, /* 45 */
 
-    XML_ERR_PI_NOT_STARTED, /* 47 */
+    XML_ERR_PI_NOT_STARTED, /* 46 */
     XML_ERR_PI_NOT_FINISHED,
 
-    XML_ERR_NOTATION_NOT_STARTED, /* 49 */
+    XML_ERR_NOTATION_NOT_STARTED, /* 48 */
     XML_ERR_NOTATION_NOT_FINISHED,
 
-    XML_ERR_ATTLIST_NOT_STARTED, /* 51 */
+    XML_ERR_ATTLIST_NOT_STARTED, /* 50 */
     XML_ERR_ATTLIST_NOT_FINISHED,
 
-    XML_ERR_MIXED_NOT_STARTED, /* 53 */
+    XML_ERR_MIXED_NOT_STARTED, /* 52 */
     XML_ERR_MIXED_NOT_FINISHED,
 
-    XML_ERR_ELEMCONTENT_NOT_STARTED, /* 55 */
+    XML_ERR_ELEMCONTENT_NOT_STARTED, /* 54 */
     XML_ERR_ELEMCONTENT_NOT_FINISHED,
 
-    XML_ERR_XMLDECL_NOT_STARTED, /* 57 */
+    XML_ERR_XMLDECL_NOT_STARTED, /* 56 */
     XML_ERR_XMLDECL_NOT_FINISHED,
 
-    XML_ERR_CONDSEC_NOT_STARTED, /* 59 */
+    XML_ERR_CONDSEC_NOT_STARTED, /* 58 */
     XML_ERR_CONDSEC_NOT_FINISHED,
 
-    XML_ERR_EXT_SUBSET_NOT_FINISHED, /* 61 */
+    XML_ERR_EXT_SUBSET_NOT_FINISHED, /* 60 */
 
-    XML_ERR_DOCTYPE_NOT_FINISHED, /* 62 */
+    XML_ERR_DOCTYPE_NOT_FINISHED, /* 61 */
 
-    XML_ERR_MISPLACED_CDATA_END, /* 63 */
+    XML_ERR_MISPLACED_CDATA_END, /* 62 */
     XML_ERR_CDATA_NOT_FINISHED,
 
-    XML_ERR_RESERVED_XML_NAME, /* 65 */
+    XML_ERR_RESERVED_XML_NAME, /* 64 */
 
-    XML_ERR_SPACE_REQUIRED, /* 66 */
+    XML_ERR_SPACE_REQUIRED, /* 65 */
     XML_ERR_SEPARATOR_REQUIRED,
     XML_ERR_NMTOKEN_REQUIRED,
     XML_ERR_NAME_REQUIRED,
@@ -109,26 +109,26 @@
     XML_ERR_LTSLASH_REQUIRED,
     XML_ERR_EQUAL_REQUIRED,
 
-    XML_ERR_TAG_NAME_MISMATCH, /* 77 */
+    XML_ERR_TAG_NAME_MISMATCH, /* 76 */
     XML_ERR_TAG_NOT_FINISHED,
 
-    XML_ERR_STANDALONE_VALUE, /* 79 */
+    XML_ERR_STANDALONE_VALUE, /* 78 */
 
-    XML_ERR_ENCODING_NAME, /* 80 */
+    XML_ERR_ENCODING_NAME, /* 79 */
 
-    XML_ERR_HYPHEN_IN_COMMENT, /* 81 */
+    XML_ERR_HYPHEN_IN_COMMENT, /* 80 */
 
-    XML_ERR_INVALID_ENCODING, /* 82 */
+    XML_ERR_INVALID_ENCODING, /* 81 */
 
-    XML_ERR_EXT_ENTITY_STANDALONE, /* 83 */
+    XML_ERR_EXT_ENTITY_STANDALONE, /* 82 */
 
-    XML_ERR_CONDSEC_INVALID, /* 84 */
+    XML_ERR_CONDSEC_INVALID, /* 83 */
 
-    XML_ERR_VALUE_REQUIRED, /* 85 */
+    XML_ERR_VALUE_REQUIRED, /* 84 */
 
-    XML_ERR_NOT_WELL_BALANCED, /* 86 */
-    XML_ERR_EXTRA_CONTENT, /* 87 */
-    XML_ERR_ENTITY_CHAR_ERROR, /* 88 */
+    XML_ERR_NOT_WELL_BALANCED, /* 85 */
+    XML_ERR_EXTRA_CONTENT, /* 86 */
+    XML_ERR_ENTITY_CHAR_ERROR, /* 87 */
     XML_ERR_ENTITY_PE_INTERNAL, /* 88 */
     XML_ERR_ENTITY_LOOP, /* 89 */
     XML_ERR_ENTITY_BOUNDARY, /* 90 */