Liffile

- Support XLIF files.
- Revise LifMemoryBlock (breaking).
- Replace LifImage.is_lof property with format (breaking).
- Require imagecodecs for decoding TIF, JPEG, PNG, and BMP frames.

- Add LifFlimImage class.
- Derive LifImage and LifFlimImage from LifImageABC.
- Rename LifImage.guid property to uuid (breaking).
- Add LifFile.uuid property.

- Support LOF files.
- Make LifFile.xml_header a function (breaking).

- Remove LifFile.flim_rawdata (breaking).
- Add index, guid, and xml_element_smd properties to LifImage.

- Fix image coordinate values.
- Prompt for file name if main is called without arguments.

- Initial alpha release.