Fix evaluation of ordered sequence of expressions in Core Erlang

Fix evaluation of ordered sequence of expressions in Core Erlang.

See Core Erlang specification v1.0.3 section 6 "Dynamic
semantics" (p. 11).

Basically evaluation of expression in Core Erlang is not a Erlang term, but an ordered sequence of expressions. In most cases it is actually a singleton expression which evaluates fully to a term. But actual sequence semantics is used for pattern matching in case expression.