Demo stability improvements

Sometimes the demo crashes, but its not consistent, and not often on my machine. Some other players have also run into crashes. So this update is to address this issue without knowing completely what the problem is. It seems to be related to the GPU and rendering API. So to fix this:

• There is now a start-up pop-up in steam that allows you to chose : Better game experience (via Vulkan) or better stability (via dx11). This can be set on every start-up, or use the same value every time.

• The renderpipeline code has been simplified to have less code that could be at the source of these crashes. Both the menu and the missions now use the same render pipeline. So there is no switching happening when moving to or from a mission. Most crashes on my machine happened just after completing a mission. So hopefully this now happens less often.

• Crash reporting has been integrated into the demo. So when a crash happens some details about the crash are send to me. This is useful to get an idea about the percentage of players experiencing crashes, and help locate crashes that don't happen enough on my own machine. It will also serve as a baseline to make sure future updates don't make it worse.

From my own experience the crashes happen only in a few percent of the play troughs. But unless you really like this game, this is too often.

Thanks again to everyone playing the demo. It is really nice to see the median playtime go up.