Fhem update

This is the last update before I want to post the SHC modules in the fhem forum for inclusion, so please test and review carefully (especially the documentation).

Main things that have changed:
1. Documention for SHC modules: 
To review execute "perl contrib/commandref_join.pl" in the fhem root folder. By running this command the commandref.html is generate automatically from the source files.

2. Notify support for dimmer device:
The define is different because of the different state string
define SHC_DIM_60_notify_on notify SHC_DIM_60:on.B:.100

3. Extended workaround
Now all false entries get deleted except "brightness", because this collides with the dimmer device where 
brightness = 0 is a perfect valid value.