error handling extracted, nicer code

also fixes mysterious errors when errors handling disappears
after first error in handleError; now finally gets to work in any case
No need for this. with createHandler
wireKlass inlined, now that was only used at one place
.meta = true shared for all metaclasses
Object.create(null) so hasOwnProperty can be ditched
Merge pull request #609 from herby/boot-js-refactorings

Boot js refactorings