Add option to allow skipping failed meter on startup

- various formatting and translation fixes
- added reparsing of config as simple fix for https://github.com/volkszaehler/vzlogger/issues/21
- added <allowskip> option per meter:

If meter open fails, meter is skipped during startup. If no working meter is found, `vzlogger quits`. 

Not done yet: if device is removed during `vzlogger` running it should fail, e.g. by timeout and quit. Help wanted!