MAINT: deprecate FeatureTable[Normalized] type

[VinzentRisch]

The type FeatureTable[Normalized] was replaced by FeatureTable[Frequency % Property("normalized", "method")].
Because of this the type can be removed.

[gregcaporaso]

@VinzentRisch, is this something you've discussed with @ebolyen? This is a little risky, b/c it's theoretically possible that it's used in a 3rd party plugin and removing it would break that plugin (and I think also break backward compatibility of existing artifacts of that type). @ebolyen - thoughts on how to proceed with this?

[ebolyen]

We should probably deprecate it instead of removing it. Although to be honest, that might be a sufficient type for our PCA problem where we want to describe Real-valued observations (which ideally exist after some suitable transform like Log-Ratio or Log of MS data) and the result of that is definitely not frequency.

[gregcaporaso]

I don't have any objection to that - if we make that change, maybe this issue should transition to adding a description of this type if we don't already have one?

[VinzentRisch]

Hey @gregcaporaso
Okay yes that is a good point then let's deprecate it. We have decided to not use this type for my purposes.
@ebolyen What do I have to do to deprecate a type?

[ebolyen]

It doesn't look like there is a way to deprecate a type. I think the reason might have been that we wanted to alias types and formats so that any existing artifacts can be "upgraded" (or maybe "downgraded" is the better word) to a known type.

In this case, maybe what we do is just update the changelog saying we are deprecating this and then removing it next cycle since I think the alias-process (which isn't implemented) is overkill for this.

[VinzentRisch]

Okay who updates the changelog? Should I let Liz know?

[ebolyen]

Just added here