Examples, improved documentation and iterators, yay!

• Added log method to domoticz object. Using this to log message in the Domoticz log will respect the log level setting in the settings file. [dannybloe]
• Updated readme. Better overview, more attributes described.
• Added iterator functions (forEach and filter) to domoticz.devices, domoticz.changedDevices and domoticz.variables to iterate or filter more easily over these collections. Starting to look like javascript already :)
• Added a couple of example scripts.