Mako88 reports that 2a19da88d4 changed
robot movement. That commit reordered the operations in a way that
tends to truncate small values prematurely. Restore the original order
of operations.
Reported-by: Mako88 <https://github.com/dxx-rebirth/dxx-rebirth/issues/247>
Fixes: 2a19da88d4 ("Pass object_base &to move_towards_vector")