[Agda] Agdalib branch needs merging

[Patrik Jansson]

The current state of Agdalib/Hedberg is a bit confusing - both the "main 
trunk" and the branch use hidden arguments. At the code sprint I 
branched off the stable library and continued work on the trunk. 
Somewhere down the line it seems like Hideaki started changing the 
branch instead. This branch should not live any longer - a merge is needed.

Michael: Could you please do the merge?

/Patrik (leaving for Thailand in a few hours;-)