alreadyPatched(): also look at the parent class loaders

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Patch the class loader containing the ImageJ 1.x classes

... not a class loader whose *parent* contains them...

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a unit test for the class loader issues

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