Batch processing model and scheduling implemented

[myxie]

TopSim now supports a batch-provisioning approach to processing workflows.

Other updates as a result of this:

• Planning is now a user-defined component of the simulation (see topsim.core.algorithms.planning)
• The Cluster may provision idle resources
• The Scheduler now provides the existing schedule to the user-defined Scheduling algorithm to update accordingly to the chosen heuristic.
• The Simulation initialisation has an updated requirement, to stipulate the planning model.

Documentation will be updated to reflect the changes in the approach to running simulation.