binding src: go back to rebuild parts synchronously, but publish only if value changes accept possible repeated eval of binding src if multiple parts change in the same cycle
binding src: go back to rebuild parts synchronously, but publish only if value changes
accept possible repeated eval of binding src if multiple parts change in the same cycle

expression-type vars and params: undo lazy eval, thus only publish if value changes
accept repeated eval if multiple parts change in the same cycle

more important to maintain:
(1) all bindings are updated in the same cycle (the next cycle)
(2) don't publish if value doesn't change (even if some part did)

ken107/databind-js,ken107/kenna-js