fhem - RGB_Dimmer: improve docu
backport SVN commit ID from fhem repo
Merge pull request #108 from Roadyweb/fhem_update

Fhem update
Use ATMega168p instead of ATmega168 (for soil moisture meter). Be aware that you need a newer version of avrdude, because the avrdude.conf of older versions does not contain the 168p.
Add soil moisture meter firmware (first version - does not measure anything).
Use ATMega 168p instead of 168 in avrdude parameter.
Add measuring of humidity (thanks to Roadyweb for example!).
Add soil moisture meter hardware layout + schematics.
Use ATMega328 instead of 168.
Add humidity message.
Use humidity message.
Add button support.
Change GPIO message format.
Switch off BOD to reduce power consumption.
Enter initialization after long button press. Remember dry threshold after averaging some values. Support averaging intervals and wakeup times from e2p config. Send battery status after given amount of cycles.
Support reading battery voltage without any external resistors. The accuracy is basically the same (~ 4.3mV at 2.2V, 8mV at 3.0V against 3,4mV with external resistors).
Support up to 6 switches in power switch. Use new messages DigitalPort(Timeout) / DigitalPin(Timeout) (partly implemented).
Mark messages as deprecated.
Update max number of switches in e2p to 6.
Rename file.