Ue4 Engine Upgrade + Other Improvements

Hi everyone,

This update includes the new engine upgrade and there are no known bugs on supported machines. If you think you've found a bug then please email dearapothecarygame@gmail.com.

Changes:
- Music Slider in Pause Menu can now go to 0 to turn music off entirely.
- Fixed various bugs brought on by Unreal Engine upgrade (4.19 to 4.21).
- Changed font and font colour on all parchments with white writing back to black. If anyone has issues reading anything, please let me know.
- Environment improvements.
- Fixed rotation on Wall Texture with windows.
- Various Lighting Improvements.
- Added more artwork.
- Added more windows.
- Added poetry book.
- Added Win/Lose SFX.
- Added dice SFX.
- Added two new songs.
- Decreased overall game size, Linux build size reduced by half.
- Linux build now supports Vulkan. From testing, I have had better performance on Vulkan.