Revert "more work on exceptions, throw enters infinite loop though"

This reverts commit bfdf00cf93bcf2c25d99c53ed73f66c2389131a6.
Revert "implementing exception handling, not working yet"

This reverts commit 0d91ef4012782e6164b16659fa37f4366e204e0f.
bug noted: dup doesn't check if stack is empty
memrange not private
safeget better error reporting