entries: Remove duplicates

[asiekierka]

Will solve #134

[dag7dev]

@asiekierka @avivace how has the cleanup been executed? Using a particular cleanup script? I remember doing similar work, but it was discarded at the time. #157
(for the sake of curiosity and clarity, nothing more!)

[asiekierka]

I edited every single duplicate entry by hand. That's the only way to ensure the "best" version of a given entry is preserved. Sometimes, I had to combine information from multiple entries.

[dag7dev]

@asiekierka I agree with you! I did the same thing at the time, and I remember this comment (#157 (comment)) where "at most 30 items were allowed".

Is this policy changed since then?

[asiekierka]

I wasn't aware of that policy :-) However:

(a) I split it into multiple commits, so they could be PR'd and reviewed separately if need be. I think the biggest single commit tackles 40 items total.
(b) I didn't do any other changes, which is why my PR has 635 diffs and not 2000+. Much smaller, thus easier to review.