Remove metadata inconsistencies for event based tracing:

- use Java naming conventions, i.e. use "oldValue" instead of "old_value"
- remove redundancy in naming, i.e. "GCGarbagaCollection" and suffix "Event"..
- avoid abbreviation, i.e. use "allocation" instead of "alloc"
- avoid reserved Java keywords in field names, i.e. "class"
- use same data type as exposed in Java, i.e modifiers as int
- don't use end punctuation in single sentence descriptions
- keep labels short and use headline-style capitalization
- use Java name for relation ids

Also, remove the unused TRACE_KLASS_DEFINITION macro