Fixed some constness problems with the bimap that does translation from PlaceKey to the internal place descriptor for ExplicitTransitions.
New local marking does not depend on the PlaceKey. This compiles.
implemented transfer_by_stochiometric_coefficient.
This version runs sirmixed without problems.
All demos now run.
The State is now split into User and system, so the user can put whatever they want in there (and so can the system)
The brownion was using a class from detail. No good. Got rid of it.
Now pass t_enable and t_0 (the firing time) to transitions when checking whether they are enabled. If te<t0, then they were already enabled.
Modified install docs and comments in sir_mixed.cpp to make more sense with current system for compiling and building types.