added pause/resume to Tracker.cs

[martinmmueller]

Motivation for the Pull request

I wanted the option to pause and resume trackers without dumping the data that was already collected (StartRecording creates a new DataTable), so I quickly built in a Pause and a Resume function with an enum-based state to keep track of what the tracker is currently doing.

Maybe this could be useful to others as well, so I thought I'd put the edit up here.

Some notes:

• I realise the state enum I added makes the 'recording' field kind of redundant but I left that in place to not break any possible dependencies.
• I added some debug warnings for telling the tracker to start/pause/stop etc. when it does not really make sense. Ideally the tracker would only react to commands when it is in the matching state in the first place, but I did not want to change too much about the base class, so I left it at warnings for now. If those don't match your policy for logging/ error handling they could be escalated to full Exceptions (like you do in RecordRow), or just removed so the Tracker just silently does its thing.

[jackbrookes]

Looks good other than minor tweaks

[martinmmueller]

Hey, thanks for the fast reply!
I implemented the changes as you requested, but I changed the calls to the recording field in checks (e.g. in Update()) to calls to the Recording Property (which now wraps the the state check as you suggested) instead of making the explicit check every time. I think it should be more readable this way.