Clean up and merge branches

[TiarkRompf]

Current stale branches:

• [x] https://github.com/feiwang3311/Lantern/tree/TensorTuple
• [x] https://github.com/feiwang3311/Lantern/tree/dev_file_scanner
• [x] https://github.com/feiwang3311/Lantern/tree/tensor_ref
• [x] https://github.com/feiwang3311/Lantern/tree/xilun_attempt

[feiwang3311]

asked xilun to check if he still needs his branch

[XilunWu]

I have made a local backup for my “xilun_attempt” branch. You can remove this remote branch now.

[GSAir]

You may want to remove all the big files from the repo. And note that removing them doesn't remove them from history so the repo is still big.

https://itextpdf.com/blog/how-completely-remove-file-git-repository