Add support for SML_EDL40_P transparency format

[ahzf]

Some customers want to use Chargy for charging stations using the EDL40+ format (e.g. EMH energy meters).

[x] Documentation of EDL40+ received
[ ] Support EDL40+transport via SAFE XML container
[ ] Support EDL40+transport via chargeIT JSON container
[ ] Parse and display Mennekes transparency data
[x] Verify EDL40+ signatures (already done for chargeIT charging stations)