Remove old documentation system

Remove old documentation system

Original commit message from CVS:
* README-docs:
* configure.ac:
* Makefile.am:
Remove old documentation system
* gst/gst.defs:
* gst/gst-types.defs:
Updating defs files
* gst/gst.override:
Wrapped gst_flow_get_name() for const-gchar *
* gst/gstelement.override:
I really should test everything on 32 AND 64 bits systems...
* gst/gstevent.override:
Updated gst_event_new_seek() wrapper
Added gst_event_get_structure() wrapper
* gst/gstmodule.c:
Changed definition of gst.CLOCK_TIME_NONE to wrap GST_CLOCK_TIME_NONE
* testsuite/testhelpermodule.c:
gst_event_new --> gst_event_new_custom