- Move render.Rpt to test.Report
- Remove report/report_fixture_test.go; it was unused
- Remove report fixture in app/ and make tests use test.Report
- Move expected outputs into render/expected, so they can be reused

- All HostMetadata information becomes NodeMetadata
- Significant change to mechanics, but same net effect
- LocalNets becomes "local_networks", space-separated list of CIDRs
- Load becomes simple single string
- Use MakeHostNodeID for indexing into Host topology
- (That changes the app /origin/{id} handler; will be removed later)