Two more lowercase field names missed by r13038, both found by checking
the uilib layer rather than only json.c/xml.c: a second OPTIONS emitter
in ui_json/uilib/uilib.c, and CLEAR's todefault. All emitters now use
one casing for scalar fields; TitleCase names like Fields and
MenuCommands are nested payloads and are left as they are.
.NET: MENU over the wire, checked against what the C runtime actually
emits rather than against the source - which corrected three things.
The objects nested in MenuCommands carry no "type" field, their ids are
1-based, and they include KEYS and HELPNO. That needed a UiPayload /
UiMessage split, since only top-level messages carry a verb.
Menu commands are identified by a caller-supplied enum, so generated
dispatch reads as "case MainMenu.Customer" rather than the old
"case 0: /* COMMAND */".
