Independent new and legacy generation trace facilities, step 1/2: keep and populate with trace information separately. still single entry point for UI to pick up the trace info.
Trace collection separate from UI presentation builder, so that trace can be used with non-UI scenarios.
Merge remote-tracking branch 'origin/master' into 3.1/artem/default
Generator: refactor ProgressManager use. Natural way to pass/use pm - long-running methods instead of cons arg. Dubious (and duplicating) CancellationMonitor dropped - cancellation from within a generation task is pretty much enough, and there seems to be no reason to duplicate this cancelled check from the  thread pool (it doesn't look like thread pool's responsibility, after all).
Refactor: bad design - method to return config value is replaced with a wrap task
Drop methods deprecated since 2007
Drop lang.generator/stucture.GeneratorDescriptor which is deprecated since 2011