Primitive frame-rate helpers.

These helpers keep frame duration and frame-count calculations explicit.

Examples

use use_frame_rate::{FrameRate, frame_count, is_standard_frame_rate};

let rate = FrameRate::new(24.0).unwrap();

assert!((rate.frame_duration_seconds() - (1.0 / 24.0)).abs() < 1.0e-12);
assert_eq!(frame_count(2.5, 24.0).unwrap(), 60);
assert!(is_standard_frame_rate(23.976));