docs/manual/: Update (until threads/scheduling) Application Development Manual; remove GstThread, add GstBus, add sim...

Original commit message from CVS:
* docs/manual/advanced-clocks.xml:
* docs/manual/advanced-interfaces.xml:
* docs/manual/advanced-metadata.xml:
* docs/manual/advanced-position.xml:
* docs/manual/advanced-schedulers.xml:
* docs/manual/advanced-threads.xml:
* docs/manual/appendix-porting.xml:
* docs/manual/basics-bins.xml:
* docs/manual/basics-bus.xml:
* docs/manual/basics-elements.xml:
* docs/manual/basics-helloworld.xml:
* docs/manual/basics-pads.xml:
* docs/manual/highlevel-components.xml:
* docs/manual/manual.xml:
* docs/manual/thread.fig:
Update (until threads/scheduling) Application Development Manual;
remove GstThread, add GstBus, add simple porting checklist, add
documentation for tag writing, clocks, make all examples until this
part compile and run.
* examples/manual/Makefile.am:
Update from changes to Application Development Manual; add bus
example, remove thread example.