- Introduce the concept of the graph state bitset: This is a set of flags that indica...

- Introduce the concept of the graph state bitset: This is a set of flags that indicate the current "state" of a graph.
  (Used so far to indicate wether muxes are lowered and should not be touched anymore and wether architecture dependent mul and div with constant implementations are used)
  We should use this to indicate dom/loop/... consistency in the fututure
- fixed a bug where lower_mode_b was creating a "set" instruction with the help of a Mux. (Maybe we should create a new Node for this and not use a 0/1 mux?)

[r25937]