Model simplifications

[magoorden]

In this issue we can collect possible model simplifications in order to reduce the size of the generated model. Whether to apply these simplifications should be an option (with default on). If one wants to see the result exactly replicating the transitions from the theoretical definitions, one should be able to turn these simplifications off.

• Remove transitions labeled with a false guard.
• Remove the printing of true of a true guard.
• If there are two edge $(l_1, a, g_1, c, l_2)$ and $(l_1, a, g_2, c, l_2)$ (observe that they have the same source state, target state, action, and clock reset), then merge them into a single edge $(l_1, a, g_1 \vee g_2, c, l_2)$.
• Remove unnecessary diagonal constraints, see Remove unnecessary diagonal constraints during guard printing #51.
• Remove the printing of true as an invariant.

Feel free to mention more simplifications if you can think of one.