Use nicer error message if plugin refuses to initialize

git-svn-id: https://pascalinterpreterinjava.googlecode.com/svn/trunk@303 fb5b4802-194b-0410-9e11-5134f6b347ec
refactored type code, to introduce Class types

git-svn-id: https://pascalinterpreterinjava.googlecode.com/svn/trunk@304 fb5b4802-194b-0410-9e11-5134f6b347ec