Deprecation frontmatter properties from 0.8.0

[Edo78]

Some properties may not be useful and should be deprecate starting from 0.8.0:

• body_hash contains the hash of the original content of the note but as the plugin is now able to detect any changes in the text this isn't going to be used

I haven't already decided when to remove it/them but I'm in no rush to do so.
Feel free to report any use you may have for those properties and we'll discuss about them