Upgrade nixpkgs and GHC

Closes #3

See merge request !5

This commit fixes the c2hs calls for the clique functions, as igraph
switched to be using a igraph_vector_int_list_t.

This commit fixes more occurrences of an `igraph_vector_t` being
erroneously used in place of a `igraph_vector_int_t`, introduced in
newer versions of `igraph`.

This commit switches to be using 0.10.4, fixing most API changes along
the way. It also stops vendoring igraph, in favour of the system
library, which now needs to be installed.

Implemented some more functions