touch up type safety in types.def
remove old function-based accessors
formalize Machine::roots in types.def
formalize MyProcessor::roots (for Compiler) in types.def
generate new setters in type-generator
use setters in util.cpp
use setters in classpath-common.h
use setters in compile.cpp
use setters in machine.h
use setters in machine.cpp
don't mark nogc fields
finish using setters
remove some unnecessary reinterpret_casts
retypedef object to GcObject*, remove almost all unnecessary reinterpret_casts