Persisting constants only if flag is set.
Basic forced autoloading for maglev_persistables.

Currently works only for one autoload per module.
Calls to autoload are cached, so that persistent associations can be created during
the call to maglev_persistable.
Turned autoload cache into a list, so multiple autoloads can happen in module.
Autoloads are automatically reloaded when called maglev_persistable is called.
Removed unecessary check of persistence mode in Module#removeConstant.

This is checked twice, because it is checked again in the line
'rns removeConst: aSymbol'. See implementation of removeConst: in RubyNameSpace
and RubyTransientNameSpace.
Commented out missing maglev_persistable(true) constants check.
refactoring: new method for persisting autoload cache
refactored: calling _persistAutoloadCache once at the end of _setPersistable method
refactoring: added new method _persistClassMethods
refactored: added new method for persisting included modules
Added tests for autoloading persistence.
refactored: new method for persisting singleton classes in _setPersistable. added newlines at the end of the files
commented out the remove contant transient mode error - only for nicco
setPersistable: Persist class methods needs to stop at module.
setPersistable: persist included modules needs to call setPersistable both on meta module and virtual module.
setPersistable: persist methods should not persist methods for module, as module is already persistable and this leads to strange errors.
Persisting constants again.
Refactored persistSingletonClass.
Refactored persistSingletonClass even more.
Rewrote persistIncludedModules to only included desired modules and "jump over" unwanted.