put dupe detection backtrace parsing in a qfuture

this previously ran on the GUI thread but is potentially a costly operation as we parse the entire data set all at once (as opposed to the live tracing as that is done as new lines arrive). this then meant that the GUI was intermittently locking up when dealing with particularly egregious traces (or generally very long comments really).

to remove this problem we'll simply run the parsing in a thread on the threadpool as thankfully the parser is one of the few classes that doesn't rely on the mountain of singletons we have.