Switch CC*.pp functions to the CCFormat.list convention

[Gbury]

The CCFormat.list function now takes unit printers for separators, which is quite useful once you get used to it.

However, specific printing functions (such as CCSet.pp, CCArray.pp, etc...) still uses strings for the separators, so I think it would be nice to switch them to use the same signature as the CCFormat.list function.

[c-cube]

This would break compatibility. I get the sentiment, but it's not high in my priority list for now… Sorry.