On screen logging

[mdales]

This PR attempts to address #93 and #91 - moving logging from Claudius from the terminal into the Claudius display. This turned out to be more messy that I'd anticipated, as it exposed some side-effecty bits of code and global state.

• Removed global variables from base.ml into a state type that is not global, but part of the main inner loop.
• Added logging structure to Stats.mli to hold log messages
• Unifies the input for handling F keys
• Updated Stats.render to draw logging
• Updated parts of Claudius that used Printf.printf to instead return a result type that has an error message which can be logged.
• Added code to Palette.t to work out two most visually different colours
• Code churn in Palette.t to reduce pollution of Int32.t
• Adds hsluv as a dependancy for colour space conversion

[pawaskar-shreya]

Got introduced to a new library! 🙌🙌

[pawaskar-shreya]

This is such a great addition to CLaudius. 🤩💫

Feels like a lot of features are being delicately tied together to have this log stats rendered to the sdl window.

And the idea with the color space is such a cool thing!

Firstly it is visually better than a single color being used in terms of visibility and secondly, it looks so much better with 2 colors being used for the log, one for the text body and other for the border. This again fits so perfectly with our theme for a retro console! 🤖

Such a cool PR this is! 🫡