Save files

[Xottab-DUTY]

Current saves format has some problems, like lack of versioning (saves are tied to A-Life version mainly).
We can make new one using modern C++20 tools for serialization/deserialization.

• Introduce a new, modern and versioned format
  • It should be compatible with original game scripts.
• Make compatibility with original COP 1.6.02 saves
  • Compatibility with OpenXRay saves is questionable. We weren't tracking changes by changing A-Life version, so several versions of the engine have different data in saves, but there's no way to determine that.
    • We probably can make a tool to convert old OpenXRay saves
  • If compatibility with CS and SOC saves is possible, it should be tracked in Launch Clear Sky #382 and Launch Shadow of Chernobyl #392