In-memory log buffer

[anatoly techtonik]

FarColorer has an option to provide log file. I don't think it is useful to have a separate log file, and I also don't like them, because they unnecessarily damage my SSD. Also you may often end in a situation when something bad happened and you don't have log enabled.

Therefore it would be useful if FarColorer just maintained the last 20kB of log data in memory and provided a quick way to pop up and see it, for example, when there are errors in parsing scheme database. The same screen can then be used to control verbosity and of collected data for subsequent runs.