Small extensions and fixes. We are now very close the old functionality level (from before the rewrite)!

* [QSIM,DEB] Extended the debug script.
* [QSIM_BUILD,FIX] Triple was written to the wrong graph.
* [QSIM_EXPORT,EXT] The output graph of export_state/3 can now be uninstantiated (a new graph will be created based on the given input graph).
* [QSIM_EXPORT,EXT] Add the relation between states and statements to the state export.
* [QSIM_READ,SC] Added qsim_statement/6. This simplifies state export in module QSIM_EXPORT.