* parser.c include/libxml/parser.h: adding a new set of
  API for parsing xmlReadDoc() xmlReadFile() ... xmlReadIO()
  and xmlCtxtReadDoc() ... xmlCtxtReadIO(). That with
  a clear define of xmlParserOption, xmlCtxtUseOptions()
  should simplify custom parsing without being tempted to
  use global variables, and xmlCtxtReset() should allow reuse
  of a context for multiple parsing.
* xmllint.c: switched to use xmlReadXXX, allow options to
  be used simultaneously with less troubles.
* tree.c: simple warning removal
* doc/apibuild.py: small fix
* doc/libxml2-api.xml win32/libxml2.def.src: updated
Daniel