Daily file appender improvements: reading already written logs at startu...

Daily file appender improvements:

*  on startup: read of already created log files for keeping to write on the latest available log file (it was buggy if rotation inside a day occurred);
*  added rotation over days;
*  removed hours/minutes accounting for rotating (it's a daily transport).

Notes on stability:

*  date patterns: tested *only* against default date pattern (that is enough for me), should work well anyway with other patterns supported by the classic version;
*  in-day and over-days rotations tested manually (it could be great to add some unit tests...).