Add default screen size

[Fantoom]

Should close #139

[ForNeVeR]

Does this work for you? For me, any of the following calls yield 0:

• Raylib_CsLo.Raylib.GetCurrentMonitor()
• Raylib_CsLo.Raylib.GetMonitorWidth 0
• Raylib_CsLo.Raylib.GetMonitorCount() (wat?!)

[ForNeVeR]

Accessing any of those requires a call to InitWindow, apparently 😓

[Fantoom]

Ah, I have forgot about it , what solution do you suggest?

[ForNeVeR]

Ok, after a small discussion, I'll finish this work.