Have virtualSize default to windowSize when not specified

[ByteAtATime]

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I'm new to Korge, and I found a really confusing feature yesterday. I had a 1920x1080 screen (that I specified with windowSize), but when I drew a 1000x700 rectangle it almost covered the whole screen. I later realized that I also had to specify a virtualSize. I propose that, when virtualSize is not specified within the Korge() function, the Korge.Config dataclass, or the Module, it should default to the windowSize.

[ByteAtATime]

Also, on a related note, I would like to help with documentation. Is there anywhere I could start?

[soywiz]

@PlanexDev You can contribute to the documentation here: https://github.com/korlibs/docs.korge.org