Added option to save log to file.
Revert "Added option to save log to file."

This reverts commit 5b7989a3f7f4ea30bea385a6e148f218d8aa135c.
Changed SimpleGuiLogHandler to MsgBoxLoghandler.
Added some documentation to MsgBoxLogHandler contructors.
Renamed MsgBoxLogHander unit test method.
Added toString(), equals() and hashCode() to LogLevel.
Added initial WindowLogHandler and its test.