app.htm: use `con` as shortcunt for console; don't check for it to be an object
app.htm: verbose `l10n` loading
app.htm: reset loadmask of shortcut button if subapp launch failed
app_back,/lib/*: rework use of `console.log` globally; use no `console.error`

* no `console.error`: if there are two streams of data then context of
errors can be lost, because part of info is in `log`, part in `error`
BackendTools.js: move OOPS message into `l10n` files
mongoDB: config, api, initial move form old codebase