Going with dark mode at first,
I'll also be making a lightmode, but I want to have a post-processing shader for tonemapping the app screen's tone by the user before doing so.
Saw that layout really should be separated from the style struct, so went ahead and pulled the trigger...
A bunch of other refactors have also been done
* Lifted layout out of style, its not separate in UI_Box and in UI_State there is not a UI_LayoutCombo stack.
* UI_StyleTheme renamed to UI_StyleCombo
* UI_Theme has both UI_StyleCombo & UI_LayoutCombo
* Made files for the "project" related code
* ui_layout_compute moved to its own file, ui_layout now used for layout related data structures and interfacing
* Impovements to horizontal & vertical box impl
* UI_Box now keeps track of how many ancestors it has
