[trivial] change the vtable to meaningful name.
remove iallocator and remove the macros used in oallocator
change iterator to iobject based.
really dangerous change,

1, skiplist related are temporarily unloaded.
2, bugs in itr_get_ref
3, bugs in imset test
4, not clear if it is possible to pass by value, and how to pass
pointers.
now the test is passing with amount of memory leak, which is caused by the ilist's front back, and iqueue, istack releated method.