Stereoscopic mode added

[AndrewGDX]

Added a native stereoscopic 3D rendering support, it fully works and configures via graphics menu.

1. All stereoscopy logic is inside LUS project, but menus code are inside SOH.
2. There are some minor geometry fixes - there is detection when certain objects starts to render in SOH project, and the fix itself is inside LUS project. Fixes are for incorrect sky depth and incorrect pre-rendered 2D backgrounds depth.
3. I tried to make as little code changes as possible, sacrificing possible performance optimization (no instanced rendering). But this is not a small change, and it probably could be implemented in much better way.
4. Minor issues: the settings menu itself is not rendered in stereo, the 3D intro logo is not in the same depth as the text.

PR in LUS: Kenix3/libultraship#1186