cleanup, always initialize complete struct when getting from xml

This has two advantages:
1. better forward compatibility, new attributes will be initialized
   even if our xml converters are not up-to-date yet.
2. simplify initialization of share pointer members
from_xml funcs don't inititialize the structs at all

Now The caller has to initialize them and actually we are always doing this
already.
from_xml funcs don't re-use member pointers
cleanup, "else if" xml children
cleanup, from_xml funcs only check XML_ELEMENT_NODE children
cleanup, for loop cosmetics
cleanup, more generic TagValueList xml converters
Merge branch 'xml_cleanup' into next

* xml_cleanup:
  cleanup, more generic TagValueList xml converters
  cleanup, for loop cosmetics
  cleanup, from_xml funcs only check XML_ELEMENT_NODE children
  cleanup, "else if" xml children
  from_xml funcs don't re-use member pointers
  from_xml funcs don't inititialize the structs at all
  cleanup, always initialize complete struct when getting from xml
xml, add some (not yet all) of the new ib api 9.67 fields

... orderComboLegs are still missing.
xml, add xml converter for OrderComboLeg (api 9.67)
xml, handle new field orderComboLegs (api 9.67)
Merge branch 'ib_proto_9.67' into next

* ib_proto_9.67:
  xml, handle new field orderComboLegs (api 9.67)
  xml, add xml converter for OrderComboLeg (api 9.67)
  xml, add some (not yet all) of the new ib api 9.67 fields
xml, add new api 9.68 fields
Merge branch 'ib_proto_9.68' into next

* ib_proto_9.68:
  xml, add new api 9.68 fields
Merge branch 'next'

* next:
  xml, add new api 9.68 fields
  xml, handle new field orderComboLegs (api 9.67)
  xml, add xml converter for OrderComboLeg (api 9.67)
  xml, add some (not yet all) of the new ib api 9.67 fields
  cleanup, more generic TagValueList xml converters
  cleanup, for loop cosmetics
  cleanup, from_xml funcs only check XML_ELEMENT_NODE children
  cleanup, "else if" xml children
  from_xml funcs don't re-use member pointers
  from_xml funcs don't inititialize the structs at all
  cleanup, always initialize complete struct when getting from xml
update ChangeLog