Add new V3.0 version of PZEM004T, not tested. Default to factory default address 0xf8, configurable through pzemv30Addr 8-bit number
Add 'frequency' measurement & 'hz' unit
Add pz.address that configures address
Implemented energy reset
Right now we only support a single device. No way to test this properly (mostly, how exactly we need to connect this stuff), so left as not implemented.