Provide cumulative sensors as well as the "today so far" counters

[Kallb123]

Is your feature request related to a problem? Please describe.
Using the current "Today" sensors within the energy dashboard results in flawed data at midnight. The dashboard expects ever-increasing data, like a meter reading. Whereas the sensors currently reset each day and provide a saw-tooth data set.

Describe the solution you'd like
Add an additional sensor to provide cumulative data that doesn't reset.

Describe alternatives you've considered
For now I'm likely to use NodeRed to detect the midnight reset and then keep track of incremental usage through the day, this can be added onto a total that keeps increasing.

Additional context

[ColinRobbins]

Are you seeing the issue for both gas and electricity?
I've integrated both, but am not seeing the issue.
What version of Hass are you on?

[Kallb123]

I'm currently on HASS 2021.9.7
Yes it's on both types of fuel. You can see that there's a reduced amount at midnight on electricity and you can see the massive negative spike on the gas.

The entities have been unavailable for a couple of weeks now and I've not bothered trying to fix it since the Bright app is only showing me days from yesterday.

[ColinRobbins]

The entries unavailable problem is issue #14.
I will shortly be creating a pull request, as I have a fix running locally.

[ColinRobbins]

I have removed the pull request for entries unavailable problem is issue #14. but fixed the issue in my fork.
The reason for fixing in a fork this is discussed here

[ColinRobbins]

I now have the cumulative sensors implemented in my test system.
Need to let it run for a few days to make sure the Energy integration works OK with it.
If all goes well, I'll make a PR.