Fix compile error

Darn Eclipse. It showed the error only after a refresh, but not before.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Suppress compiler warning

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a class helping with casting interfaces between ClassLoaders

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>