Unvivtool

* improved performance

* Python: get_info() returns dictionary of entire archive header data

* De/Encoder: provide endianness and other info, improved performance
* Python: more informative get_info()

* Decoder: much faster, reduced memory consumption
* Python: new function returns archive metadata
* C: provide new functions LIBNFSVIV_GetVivDirectory*() and LIBNFSVIV_VivDirectoryToFileList*()

CLI: release archive includes win98 (x86) and x64 executables
Python: improved performance
Python: drop Python 3.9 support

* De/Encoder: improved filesystem behavior, especially on ancient Windows
* Decoder: add overwrite mode (auto rename existing files)
* Decoder: create non-existing output directory
* Decoder: never overwrite archive
* CLI: passing an output directory to decoder is optional, and it need not exist
* CLI: command-line options ``-dnl`` ``-i`` ``-f`` ``-fmt`` and their respective arguments are no longer separated by whitespace (breaking change)
* Python: easy installation via ``python -m pip install unvivtool`` on Win, Linux, and macOS