refactor adding webCmds and devStateIcons

use lookup table do define webCmds and devStateIcons
refactor state string creation

use lookup table do assemble state string
refactor set commands

define a array with device specific set of cmds and check against
allow to set the devtype through a new set command
bugfix: remove invalid barometric pressure reading

Without receiving the BarometricPressureTemperature message a barometric reading
gets added. This happens especially after a fhem restart. The root cause is not easy to debug and still unknown. Add this workaround to avoid wrong/invalid entries
in the device reading table
refactor automatic device type assignment (now . delimiter)
add distance to fhem state string
proposal for extended command set implementation

(independent of device type)
Merge pull request #69 from Roadyweb/fhem_refactor

Fhem refactor