Changed the Weighted compare for F32
Changed the Weighted compare for Vec
Changed the Weighted compare for Indices
added Indexed Images and functions
Changed Database that it uses Indexed Images
Added tests
Added the rgb_to_lab function
added pixels function
* added multithreading crate with thread pool
* added crate mutlithreading
* replaced `threads` memeber from `Threadpool`
mutex with atomic primitive
* fixed doctest for threadpool
* added module documentation to multithreading
* added functionality to drop thread handles
automatically when threads have finished
* reformatted crate `multithreading` to pass tests
* added benchmark for `threadpool`
using `criterion`.
* finished benchmark for threadpool
and fixed documentation for threadpool
* added unit test to `multithreading`