ArrayVar.value_= now supported
split OrdinaryProcess into ODE and ODEIntf
added method next to DiscreteProcess
splitted Process into BaseProcess and Process, and replaced VarConv by trait VarConversions.

also committed changes to file SchedulerTest.scala that I forgot in last commit.
splitted DoubleVar into DoubleVarIntf and DoubleVar
added ReactionNetwork and DeterministicReactionNetwork
added .gitignore
merged ww's changes