fix: resolve an issue with `getBox` type

feat: add wave box from quicktime

closes #505

fix: handle mp4a in quicktime mode

fixes #505

feat: implement writing logic for `dOps`

fix: correctly detect fragmented files

- Display total fragment duration on the demo

closes #504

fix: prevent an infinite loop in processSample

fix: better type inference via getBox(es)

relates to #499

fix: off by one errors in box and field size calculations (#498)

fix: handle the case where getSample is called but mdat was discarded

added extra warnings to warn user beforehand

closes #496, closes #492

fix: use int32 for `mvhd` matrix