Improve number input

[mark-prins]

Fixes #287

I've removed the tight coupling between the text input and the value, which was also being limited by the min/max constraints.

This means that when you edit a numeric input, you can clear the input and type in a number larger or smaller than the allowable. When you save though, the value saved is the one entered which is in range. Hopefully if you try it you'll see what I mean.

For example, when editing a temperature (which has a minimum value of 1) this sequence can happen:

1. the initial value is 30
2. you backspace twice to clear the value
3. you click OK
4. the value of 3 is saved, as this is the last valid value

It is hard to explain but I think makes more sense when using it than the previous, which prevented the input value from changing.

The affected areas are:

• Default logging interval
• sensor logging interval
• temperature breach settings (x4)
  • temperature
  • duration

You can test this and #296 with this apk

[jmbrunskill]

Keen to see how the testers feel before we merge this one...

Sounds better, but could also feel quite buggy :(
Number inputs are much harder than I ever though in the past!

[mark-prins]

@jmbrunskill thanks for review! have checked in with @marthakeezy and she has given her blessing 🙏