Add expanded labels for units

[MrD-RC]

This PR adds expanded hover labels for units.

[Jetrell]

Pitch to Throttle ratio is explained as a ratio, therefor it has no unit... But it appears to be calculable in uS?

[MrD-RC]

@Jetrell Yes, you're right. It should be in uS. But you've now got me thinking is Ratio the correct term? It multiplies the pitch2thr value (which is throttle in uS) by the pitch angle. It's a multiplier rather than a ratio surely?

[Jetrell]

I think it depends if its easier for a person to view it as an equation, or an interaction between variables.
In its simplest form. Its how many uS of throttle are changed per degree of Pitch offset from a level attitude.
But due to this value also being constrained by nav_fw_min_thr and nav_fw_max_thr ... I think a Ratio may encompass all of that better.
Does that seem right?

But, is it a Pitch to Throttle ratio (P2T) or a Throttle value changed, as a result of Pitch (T2P)?

Something I haven't tested. Is the P2T value constrained?
If someone was to entered a value like 50 (5% ). That would give a 50% throttle increase for 10 degrees of pitch... rather extreme.

We understand why its in uS.. for resolution. But I wonder if it would be easier for the average person to understand.. e.g. a value ratio of 5, being written as 0.5% throttle change to 1 degree of pitch change?