Hoymiles inverters allow setting relative limits with a precision of 0.1 %.
this changeset allows to utilize this precision.
* preserve accuracy when decoding power limit
* Web API: process floating point limits
* MQTT: process floating point limits
* use appropriate accuracy for limits in web UI
* HASS: step for relative inverter limit is 0.1 %
Added additional field to the prometheus api which identifies a channel by it's type. That means that e.g. channel 0 exists for type AC and DC.
This commit also introduces a additional field in the statistics byte assignment table. This field identifies whether a channel is on the AC or DC side. MQTT and WebAPI is still compatible with the previous design.
