Add mutex to File save logic
Fix #41: Problem in current callback implementation. Add dictionary for current records per Runspace
Don't throw error to background job: it's not actionable for user, but just stopping job
Fix mutex logic
Replace Thread.Sleep logic by Timer. Reduce disk write operations freaquence
Merge pull request #42 from vors/release-0.6.0-41

Fix for #41 + file save logic reliability enhancements