Added LogTimeout method
Simplified WPF error handling and tracing

The former method FL.RegisterWpfErrorHandler did two things: Register the Dispatcher's UnhandledException event handler and add listeners for all PresentationTraceSources. The error handling is now done in any case on the base class of Application, Dispatcher, so the Application instance itself is no longer needed. The tracing method has been renamed to RegisterPresentationTracing and can be called at any time, like when confirming the log path at the application entry point.

Existing WPF applications need to change this single method call when using this revision of FieldLog. (See the change in FieldLogViewer for reference.)
Custom timers: Optionally do not increment the counter

This can be useful when multiple code segments shall be timed in a group.