Features
- Provide band information on all tile sources ([622](../../pull/622), [623](../../pull/623))
- Add a tileFrames method to tile sources and appropriate endpoints to composite regions from multiple frames to a single output image ([629](../../pull/629))
- The test tile source now support frames ([631](../../pull/631), [632](../../pull/632), [634](../../pull/634), [634](../../pull/634))
Improvements
- Better handle TIFFs with missing levels and tiles ([624](../../pull/624), [627](../../pull/627))
- Better report inefficient TIFFs ([626](../../pull/626))
- Smoother cross-frame navigation ([635](../../pull/635))