Replace four complex bytecodes for building sequences with three simpler ones.


The following four bytecodes have been removed:

* BUILD_LIST_UNPACK
* BUILD_TUPLE_UNPACK 
* BUILD_SET_UNPACK 
* BUILD_TUPLE_UNPACK_WITH_CALL

The following three bytecodes have been added:

* LIST_TO_TUPLE
* LIST_EXTEND
* SET_UPDATE
