Checking course with sections

Todos:
- [x] run standalone tracer for each section
- [x] set begin/end markers/flags for each section trace
- [x] detect/reduce marker collisions with iterative process
- [x] rerun tracers for sections with reduced paths
- [x] merge trace data from all sections
- [x] call sections tracer/checker in raid app conf
- [x] display section markers in runner trace panel
- [x] load/save section trace data
- [x] permissive/greedy-loose tracer for first pass