switching to json for data serialization / wip
tries to read project in the "old" (pickled) format, if cannot read it as json
cleanup
merged develop
cleanup + numpy is out of scope
Merge pull request #61 from StarterSquad/feature/143-switch-from-bunch-to-json-for-storing-project-data

Seems to work but always saves with .prj extension even if it's a json; plus no fallback if saving to json fails (which is probably ok)