Request: `diskr/diskw` API should take `offset` as a param
In other platforms (TIC-80, Pico8, Arduboy, etc...) I'm used to persistent storage being random access.  I can read from any position or write to any portion.  The current `diskr` and `diskw` routines seem very limited in that they can only write/read a block from offset 0.  In my Arduboy2 library port this meant that I essentially had to persist all of the 1kb EEPROM in RAM to allow random access... and then just write the entire 1kb block any time changes were made. 

_This seems suboptimal._  I'd suggest expanding the API to allow passing an `offset`:

```
pub extern fn diskr(dest: [*]u8, offset: u16, size: u32) u32;
pub extern fn diskw(src: [*]const u8, offset: u16, size: u32) u32;
```