hush: finish and enable optional case...esac support. Code size cost:

function                                             old     new   delta
run_list                                            1891    2075    +184
parse_stream                                        1764    1847     +83
expand_strvec_to_string                                -      83     +83
done_word                                            647     715     +68
static.reserved_list                                 144     168     +24
static.reserved_match                                  -      12     +12
done_pipe                                             95     105     +10
builtin_exit                                          48      46      -2
builtin_eval                                         127      54     -73
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 5/2 up/down: 464/-75)           Total: 389 bytes

4 files changed