[engine] Correctly set parent and child relationships for nested coordinator registrations and root of topology tree.
[scheduling] [engine] Fix major issue that led to nested coordinators' resources not being included in the flow scheduler's flow graph. This required a bit of a re-write of some logic; this version works, but may be buggy.
[scheduling] Remove redundant output from DIMACS export.
Merging flow graph things from branch 'malte' into cost_model_merger

Conflicts:
	src/engine/coordinator.cc
	src/scheduling/flow_graph.cc
Merged changes into the energy scheduler. Everything compiling but nothing verified.