Various GUri code, documentation and API fixes
This is what I’ve come up with after going through the code this morning, with the aim of ensuring the API’s the right shape to be stabilised.
CC @malureau, @sdroege — this needs to be reviewed by the end of tomorrow so I can release for the API freeze. (Sorry for the rush, I’ve got this done as fast as I could.)
Fixes: #2149 (closed)
Edited by Philip Withnall