Add option: Disable all preset styles

[ocean2811]

Hi,

My log style is completely different from the default styles(log4net,time format,etc.).
I hope you can add a setting that makes it easy for me to disable all preset styles.

Thanks.

[emilast]

Sorry, I can't think of a convenient way to do that right now, because of how the highlighting is implemented. Will keep this issue open for now, though.