Language property sorted into 2 categories

[stephenwf]

In the IIIF Presentation 3 specification the language property is documented under 3.2 Technical properties but in the Summary of property requirements table it is listed as a "Descriptive and Rights Property".

[azaroth42]

Ooops. Need to check for this in the 4.0 rewrite.

[azaroth42]

property categories are going away, solving the problem :)