This updates `fmt` to the latest version and moves to just being a copy
of their repo to make updating easier (no editing their cmake / figuring
out which files to minimally include).
The motivation for this is now that we switched to C++ 20, there were a
ton of deprecated function usages that is going away in future compiler
versions. This gets rid of all those warnings.
* begin work
* work
* working objs
* exporting
* it works
* before some time of day fixes
* add time of day interp and also fix zbuffer
* some small blending fixes
* improve randomess
* clean up extraction and missing blend mode
* culling, time of day, more level fixes
* more cleanup
* cleanup memory usage
* windows fix
Tyler Wilding
Ziemas
water111