Removed old call to _setRubyModulePersistentBit: This is set during the call to _setPersistable.
Renamed Module#resolve_constant to __resolve_constant, because it is not part of the official api.
Merge pull request #309 from MagLev/stefan/persisting-only-maglevrecord

Possibility to persist only some modules
Module#redo_include_and_extend now returns what has been included_and_extended.
Bugfix to last commit: Handling special case nil.
Fixed #311.
Merge branch 'master-1.9' into stefan/maglevrecord