In 3.21.2 the method to compute hashes for files and directories
suddenly changed. Previously it was `FNV1A64` with lowercase paths for
files and directories having trailing slashes removed. Both path types
had a suffix of `++` appended while hashing.

The new method is instead using `MurmurHash64A` for hashing with a seed
of `0x1337b33f`. The old `++` suffix is gone and all paths (both for
files and directories) are now lowercase.

As the patch also transformed the path representation in the index file
to be all lowercase this affects the case of filenames from the listing
and filenames/patterns given on the command line.

The program can detect whether a given set of game files are old or new
based on the hash of the root directory in the path representation and
selects algorithms and logic accordingly.

If the program detects old datafiles it will go into a legacy mode with
the old case-sensitive logic, otherwise all input and output will be
lowercased.

External programs interacting with `bun_extract_file` needs to take this
into consideration.