Ufonormalizer

What's Changed
* Fix conversion of floats by madig in https://github.com/unified-font-object/ufoNormalizer/pull/90


**Full Changelog**: https://github.com/unified-font-object/ufoNormalizer/compare/0.6.1...0.6.2

Two fixes from frankrolf (thank you Frank!)

- Fixes the deletion of images by the normalizer (88)
- Does not write empty keys (89) in layerinfo.plist (or an empty layerinfo.plist)

Changes how `<notes>` are handled, the normalizer will not change the formatting of lines in a note anymore. This is backwards compatible, as it will not change any previously normalized UFOs. See 84 and 85.

Fixed bug whereby guidlines at x=0 or y=0 were being discarded (82, 83).

Fixes reporting of version number

Cleans up extra, un-need artifacts.