Initial commit.
Add missing properties from lobid that won't be discontinued.
Delete empty rows, fix formatting.
Fix deprecated MARC relator codes.

marcrel:voc & marcrel:clb are changed to marcrel:sng respectively marcrel:ctb.
add bibo and iso639-2 prefixes.
Add dct and frbr prefixes.
Merge branch 'master' of https://github.com/lobid/lodmill
Adjusted gnd context document.
Reflecting the additional properties that aren't from gnd namespace.