Avoid using deprecated functions from igraph/C

[krlmlr]

Change to #define IGRAPH_DEPRECATED __attribute__ ((__deprecated__)) and fix errors, one PR for each deprecated function.

[szhorvat]

igraph_hub_score() and igraph_authority_score() are deprecated because it makes sense to always compute these two scores together (for efficiency, interpretability and to make sure we get a matching pair). The new function is called igraph_hub_and_authority_scores().

I suggest merging these two in R under the name hits_scores(). See https://en.wikipedia.org/wiki/HITS_algorithm for where the name comes from. This name is short and there's precedence (both Mathematica and NetworkX use a variation of it).

In the longer term I also suggest deprecating the separate hub_score() and authority_score() functions in favour of the combined one (hits_scores()).

The TL;DR of this comment is a suggestion on what to call the combined function.

[maelle]

@szhorvat should this comment be a separate issue?

[krlmlr]

Running revdepchecks.