Change signs in thermodynamic force update and apply

[J-Hizzle]

Solves #36

I have implemented the requested changes, but had no better idea than to duplicate some code in the update function. If you'd have a better idea, it would be very welcome.

Apart from that, I did not look at the SPARTIAN implementation, yet. So this should not be merged right away. The tests pass, though.

[XzzX]

Solves #36

I have implemented the requested changes, but had no better idea than to duplicate some code in the update function. If you'd have a better idea, it would be very welcome.

Can be implemented like https://en.cppreference.com/w/cpp/algorithm/transform
I will provide an implementation.

Apart from that, I did not look at the SPARTIAN implementation, yet. So this should not be merged right away. The tests pass, though.

SPARTIAN is only tested by me and at some points I have doubts it is correct...

[J-Hizzle]

Can be implemented like https://en.cppreference.com/w/cpp/algorithm/transform
I will provide an implementation.

Awesome, thanks a lot!

SPARTIAN is only tested by me and at some points I have doubts it is correct...

Well, then we may disregard SPARTIAN for the time being. I won't need it in the immediate future.