Alpha ai pacenotes: rally stages & pacenotes editor v0.5.2-alpha

- Fixes major performance issue during loading of a stage due to reading driveline.json file. Previously it was reading line-by-line, and now it reads the whole file into memory and then splits into lines. This was very slow when reading from zipped/packed mod, but not unpacked.
- Changes all stages to NOT prioritize player vehicle, so that the Scenarios menu method of starting stages will load the right default cars.