Improved modem functionality

[ArendJanKramer]

This PR features:

• The ability to setup communication with car, according to ISO15118 standard
• Work together with pyPLC (https://github.com/uhi22/pyPLC) which can handle the digital communication with the car, and submit the SoC states back to SmartEVSE
• Compute the current SoC, based on the EV meter
• Reliably reset SoC values upon disconnect with vehicle
• "Re-plug" the vehicle if the communication fails, and after communication was succesfull to resume AC charging
• Display the SoC values on the web UI

Work todo:

• Set the battery capacity of the car via the menu, or via API. Currently hardcoded on 28kWh for Ioniq vehicle
• Feature to stop charging once a specified SoC has been reached
• Authorization of car based on MAC address of car

Please review and merge pr, rather than copy/pasting code. IMO git is not meant for copy-paste. I'm happy to make changes or to add code/docs where needed.

[dingo35]

@ArendJanKramer I'm afraid I'm going to have to revert your code; it prevents charging when Modem = Not present, so it looks like you never even tested without modem/pyplc present?

[ArendJanKramer]

@ArendJanKramer I'm afraid I'm going to have to revert your code; it prevents charging when Modem = Not present, so it looks like you never even tested without modem/pyplc present?

It works fine here? Normal, smart and solar seem to work, although solar is waiting as its dark here.

[dingo35]

Perhaps EV dependent? My EV didnt charge last evening, didnt have time to look at it, reverted theast commit and there it went. No EV here today so I cant try....

[dingo35]

@ArendJanKramer False alarm, I cannot reproduce the problem, it charges fine now. Might have been the EV, there are quite some bugs in my cars firmware and VAG has problems getting their software development trajectory right.... Still waiting for the firmware update that will enable modem communication....