making DSO support an option code and documentation cleanups regenerated

* configure.in: making DSO support an option
* xmlmodule.c xmlreader.c include/libxml/xmlmodule.h: code
  and documentation cleanups
* elfgcchack.h testapi.c doc/*: regenerated the docs and
  checks for new module
* test/valid/REC-xml-19980210.xml: fix a small change introduced
  previously
Daniel
40 files changed