- Improve responsiveness by downloading the smallest possible chunk
size when seeking or first loading.
- Improve download time and decrease CPU usage by downloading the
largest possible chunk size as throughput allows, still allowing
for reasonable seek responsiveness (~1 second).
- As a result, take refactoring opportunities: simplify prefetching
logic, download threading, command sending, and some ergonomics.
- Fix disappearing controls in the Spotify mobile UI while loading.
- Fix handling of seek, pause, and play commands while loading.
- Fix download rate calculation (don't use the Mercury rate).
- Fix ping time calculation under lock contention.
* Remove deprecated use of std::u16::MAX
* Use `FromStr` for fallible `&str` conversions
* DRY up strings into constants
* Change `as_ref().map()` into `as_deref()`
* Use `Duration` for time constants and functions
* Optimize `Vec` with response times
* Move comments for `rustdoc` to parse
* Use sub-crates of future
* Remove unnecessary pin-project
* Removed unused crates and features
* Replace futures channels by tokio channels
* Use serde's "derive" feature flag instead of serde_derive
