Global configuration of simulations.

Item Summary
Name	Type	Multiplicity	Description
metric	container SimulationMetricDefinitionType	[0,-1]	Explicit definition of a metric (other than implicit ones, like event-tag-based).
simulation	container SimulationDefinitionType	[0,-1]	Globally-known definitions of simulations.

Items
- metric
  
  Flags: RAM,runtime
  
  Multiplicity: [0,-1]
  
  Explicit definition of a metric (other than implicit ones, like event-tag-based). Note that currently these metrics can be defined only at the global level. Later, we may consider allowing metrics definitions also in individual simulation definitions.
- simulation
  
  Flags: RAM,runtime
  
  Multiplicity: [0,-1]
  
  Globally-known definitions of simulations. For any particular simulation, one of them should be selected. (Or a custom one may be defined.)