AlreadyAskedFor -> WaitingFor rename, for reasons of least surprise. #1341

Also, reduces confusion when combined with future pull requests.

This is a small change, and possibly seems petty, but it's useful for two reasons:

1. Principle of least surprise. Waiting can end (and does in the code), but Already Asked for requires a past event that's happened to unhappen. This is confusing.

2. Later code (which I am hoping gets pulled when finished, such as #1326) uses variables that make sense, and makes the code simpler to understand when used with this renamed mapping.

3. probably other reasons....

I know from own observations, that core devs dislike variable or function renaming without a very good reason ;), only wanted to say...

Principle of least astonishment is usually the best reason for such a change, along with naming conventions probably coming a close second (or joint first).

NAK, breaks other more important changes for little gain