Fix conversion of auto-converted resources, pack loading

[nikitalita]

• Fixed packed scene conversion for auto-converted scenes (packed scenes do not always have "_bundled" as the last property)
  • Fixes #119
• Fix version detection from directory (3.x resources also have ".converted." resources, so we can't use that to determine the version number)
• Skip MD5 hash checking if MD5 field is empty (all 0s)
• Make project config loading optional during pack loading (some games have chained packs that do not have them)
• fix removal of .converted. resources for v3 projects
• Improve finding the offset for embedded PCK files in executables
• Misc. refactoring