Fix build, improve reloader, API

[SuperAuguste]

No description provided.

[JerwuQu]

Here are some issues and ideas for improvements I've discovered.
Will keep updated as I keep poking around.

API

• blit src_x/src_y mismatch i32/u32 with the platform_specific one leading to a compiler error
• text_color for text should be optional
• blit flags should have a default
• Functions that take optionals in structs should default them to null
• red/green/blue => r/g/b since names are implicit when the type is a color
• Controls should preferably have a backing int

Watcher

• Watcher should build once directly when running zig build watch
• unable to check cache: stat file '(ROOT)/src/cart.ld' failed: FileNotFound errors when running zig build watch
• Placing the zig root source file in the root (rather than e.g. a src/ subdir) will cause the watcher to watch all files in the whole root dir, including zig-cache which causes errors and breaking the watcher whenever the cache changes
• watcher is finicky if wanting to have auto-converted assets because source assets should be watched but output assets shouldn't

Sim

• Out of bounds memory error goes off screen
• npm run dev should build and live-reload It seems to work. Maybe something was wrong on my end...