Improve understandability of article form (labels, locales, tooltips)

[twothreenine]

I've seen you've changed supplier order unit to delivery unit. Generally I'm not really happy with the texts at the moment, "Can be ordered per" does not specify whether from the supplier or by ordergroups. I think this should be clearer. My suggestions:

internally orderable per is of course meant as an alternative suggestion, I prefer the one above though.
edit: members can order per isn't too long either

Einheiten-Umrechnungen sounds very confusing to me. Inhalt would be a loose translation, but clearer, I guess. You could even use "content" in English. I think this would describe the main use case here best. Adding a ratio like ml/g will be the exception. I think we should explain how ratios can be used in a tooltip.

[lentschi]

@twothreenine Those are just initial ideas (just so we can test the multi language setup on the demo server).
I'm not sure, it makes sense to discuss each single translation here.

I suggest we finish everything in English first and then discuss translations directly in the translation files (e.g. via PR). Would that be okay for you? (If so, I'd close this issue - after all there's #23 to tackle this)

[twothreenine]

I just wanted to note this for later as I thought about it.
I think it does make sense to discuss the labels of this menu together, and the tooltip thing isn't tackled by #23.

After the current issues are solved, I'd suggest we complete the translations to German and then invite ppl from the Austrian forum for a wider test, both for understandability as for bugfinding.

[lentschi]

Okay, but please create a separate issue to discuss adding tooltips etc. I'm closing this issue now to avoid confusion.