Flecs v3.0.1

This version includes the following bugfixes:

• Fixed issue where calling set with a new pair in a multithreaded app could assert
• Fixed issue where linking Flecs as static library would cause unresolved symbol errors
• Fixed issues in cmake files for examples

This version includes the following improvements:

• Union relationships are now serialized as regular relationships by the JSON serializer
• Added README on how to run examples

Known issues:
#765
#716
#714
#620
#478
#314