Added graphical differences for System Full GC, it allows to select

Hi for all,

I use GCViewer in my work. One of the tedious and important task is to differentiate the Explicit FGC / FGC System of gc logs.

I've taken the liberty to implement graphically  the difference between both and add the Spanish language, one of the most spoken languages ​​in the world.

I hope my contribution is welcome. Thank you very much.

Àngel Ollé Blázquez