* Make slice constructor consistent
* Add more missing std::move for ref steals
* Add missing perfect forwarding for arg_v ctor
* Add missing move in arg_v constructor
* Revert "Add missing move in arg_v constructor"
This reverts commit 126fc7c524ea7a51b54720defd75de3470d69557.
* Add another missing move in cast.h
* Optimize object move ctor
* Don't do useless move
* Make move ctor same as nb
* Make obj move ctor same as nb
* Revert changes which break MSVC
