Added "JobSpecSource" as a base class for both section tree nodes and
workload entries. This adds a common interface between them for:
- Resolving names
- Storing configuration
- References to parents
- Getting IDs out of configuration
All config now uses configuration points
Config parsing is now done in destinct stages
- first all files are parsed and sent to their corresponding config objects or to a tree
- tree is traversed to generate job specs.
