Infer Schema from Structs

Instead of super verbose creation of schemas, you can now pass a struct and infer schema based on the json tags. Thanks @3jerde and @ajzo90 for the contributions!

What's Changed

• fix bug: unlock of unlocked mutex in safeWriter.Close by @ajzo90 in #1
• Inject io.Writer to the SourceRunner instead of using an internal io.WriteCloser by @ajzo90 in #2
• Nested structs and schema inference by @3jerde in #3

New Contributors

• @ajzo90 made their first contribution in #1
• @3jerde made their first contribution in #3

Full Changelog: v0.0.6...v.0.0.7