Removed generic --trace functionality from parse.js.

* Removed Tracer object from mediawiki.paser.environment
* Removed all references to tracer and its functions (startPass,
  endPass, onChunk, traceToken) from TokenTransformManager,
  TemplateHandler, etc.
* Created a warning message in setDebuggingFlags in mediawiki.Util.js.
  to notify users that generic tracing is no longer supported.

Change-Id: I1032eb0099a79182f54d0752683106884bc99db1
Merge "Removed generic --trace functionality from parse.js."