Feature request: Option to relax name validation

[knl]

Currently, I can't process in goavro data produced by an old Java application that uses Avro 1.8 library, because schema validation dies with:

Record ought to have valid name: schema name ought to have second and remaining characters contain only [A-Za-z0-9_]: Event$

Indeed, schema begins with:

{
    "type": "record",
    "name": "CreateEvent",
    "namespace": "org.apache.hadoop.hdfs.inotify.Event$",

Would it be possible to relax name validation via an option? I see there is an exported variable RelaxedNameValidation, but that one only applies for the first component, and only when the first component is empty.

[rockwotj]

Happy to take a PR that would allow RelaxedNameValidation to support nested java class names too (add $ as a valid char).