Win32: Implement "-d" command-line switch. It didn't do anything, previously.
Also added a helper func to set all log levels at once. Should be handy if we clean up the logging channels screen.
Update the DebugLog batch file so it works with the new command-line option.
Merge pull request #5777 from thedax/win32DebugLog

Win32: Implement "-d" command-line switch, and update the DebugLog batch file accordingly.