Log to file + Logfile maximum size

[janwilmans]

Feature to stream the logging directly to a file, that can then be monitored remotely using any kind of sharing mechanism, specifically, a program like WinTail (http://tailforwin32.sourceforge.net/ ) should be able to monitor the file. That means a second process should be able to read the file while debugview++ is writing to it.

[janwilmans]

class FileWriter is a work-in-process to make this possible, currently, it has race-conditions, see also #171