Screenshot is blank if resolution too high

[seichelbaum]

Problem:

• If using a too high resolution, the screenshot stays blank.
• This is a bug somehow.
  • But not directly a fault of our software

Task:

• Re-write the screenshotter in a way that it does not use OpenGL's high-res + multisampling tools, but do "manual" multisampling and split image into several smaller sized screenshots that will be merged to the large image. This splits screenshotting into multiple frame -> thus avoiding timeouts in the OpenGL pipeline,