In plasma code, it's more common to see `/** ... */` doxygen comments
rather than `/** ... **/`.
This change fixes up doxygen comment terminators to prevent inconsistency
issues.
This was done mostly because I wanted to get rid of the Resource
dependency in AbstractDataSource so I can make our xwl bridge direct,
but this also fixes up some issues with object lifespan present in the
previous version and keeps all our clipboard code in-line.
