Renaming Watchdog::get_ticks/get_millis() to ticks/millis() as RTC.

1. Ripple effect on usage of these functions.
2. Fixed error in Watchdog::await() when requested ms is less than ms/tick.
Improving DS18B20 1-wire driver; hiding parasite power handling.

1. Connect() will now read configuration and power supply mode.
2. Necessary delay on convert_request() is now hidden in read_scratchpad().
3. Additional sensor in CosaVWItempsensor example sketch.