Fix issue where Start/Stop button will not work when charging timer is active.

[glynhudson]

As per lincomatic/open_evse#88 there is a current issue with latest open_evse FW where the 'Start' button on the web UI will not start a charge if the delay timer is active.

A work around for this is to use a new RAPI command ($F1) to simulate the front LCD button press whenever the start/stop web UI button is pressed.

The Wifi gateway should first try and send $F1 whenever the start/stop button is pressed instead of $FE and $FS. If NK is returned we should fallback to using FE/FS

The new open_evse FW with F1 RAPI command it currently in testing branch and will be merged into dev branch soon. See issue above

open_evse FW V5.0.0 which includes the API changes mentioned above has now in master branch and has been released: https://github.com/openenergymonitor/open_evse/releases/tag/v5.0.0

[jeremypoulter]

Just been looking at this, on my version (D4.8.0) the $FE works fine when sleeping with the delay timer. However it is when the delay timer has triggered a timer that I see an issue, the delay timer starts the charge, I click pause or press the button, the OpenEVSE briefly goes to sleep but starts again after a few seconds.

Will update to the latest 5.0.0 firmware but we are probably going to have to do significant testing with different versions of the firmware.

It would greatly help to list the major OpenEVSE firmware versions that need supporting, along with what happens now and what is expected (from an end user POV).

[glynhudson]

Can confirm tested with open_evse V5.0.0 FW and it works great. Fixes the issue of the start button on the web UI not being able to override the delay timer.