For some reason, MSVC seems to want to instantiate these, even though
nobody ever asks for them (as evidenced by the fact that the builds
passed on other architectures).
This commit is huge, but hopefully the cognitive load is not too bad.
The bulk of this commit is just some fairly mechanical updates from
`ratio` to `Magnitude`. Other things to call out:
- `UnitRatio` goes away. We don't need this concept, because Magnitude
can't even _represent_ anything that doesn't satisfy it.
- I commented out some formatting test cases where the precise
expression changes, but the number is completely equivalent. We will
need to decide how we want to handle Magnitude formatting as a
separate, follow-on task. But at least Magnitude gives us all the
tools we'll need to do so!
We had some fun exploring the STD UDLs for potential collisions,
we have learnt our lesson and know how to proceed.
Now is high time to start behaving and obeying C++ rules.
this improves the situation for #55 (doesn't solve it outright)
motivating examples which now work are:
1q_mi * 1q_mi * 1q_mi
1q_au * 1q_au
tests added and docs updated
really finds the maximum common ration as opposed to previous algo which
simplified on the exp part of the ratio by using std::min
most of new code credit to Conor Williams
discussion and additional doc here:
https://github.com/mpusz/units/issues/62#issuecomment-588152833
test case was 1yd + 1in = 37in => added as a test
commenting out unusued ratio_add and its tests
if to be reintroduced, should also use the new gcd routines
additonal change was required to check in `safe_divisible` concept
den=1 is not sufficient anymore. reusing new gcd routines
moved ratio nomalize and new gcd routines into new, separate bits/ratio_maths.h
this resolves#62