Added command switch and enhanced time export

You can now set refreshrate directly upon launch, e.g.
"./watchdog1337.sh 50" gives a 50 second refresh rate.

Added Unix timestamp variable and made all time variables update
themselves before launching $CUSTOMCMD
Might come in handy if a plugin where to decide when the previous ping
round ended. Offered in multiple formats, see function timeupdate() in
source for details

Bumped to 1.0 RC1!
WDAlerts! 1.1

Changes:
- $VALGET is now $SELECTION (Silly norwegian-> english)
- It is now possible to set a custom $WAITTIME when WDAlerts is set to
wait in settings.cfg
The wait time is displayed in minutes on the OK and ALERT screens.
- Changed some if statements into sexy oneliners
- Updated some code comments