The object may be globally reset via the seed_rng() function.

Ressurect old edge_reciprocity code.

This fixes a bug where some matches were skipped, due to a spurious,
abrupt termination of the search.

This also changes the default argument to 'random=False'.

Images are now converted to png a posteriori for html output, but are
used as pdf for latex.

This fixes a bug in the "correlated" mode in random_rewire().

This implements a general "blockmodel" generation / rewiring algorithm,
using Gibbs acceptence / rejection sampling (a.k.a Metropolis-Hastings).

This also implements some optimizations in the rewiring code, which
makes it more efficient on filtered graphs.

This introduces several simplifications and corrections to the graph
rewire algorithm, to guarantee unbiased sampling.

Now a move is outright rejected if it produces a
self-loop/parallel-edge, instead of retried. This also adds a
"non-sweep" mode, where edges are rewired randomly, possibly with
repetition.

The edge moves are now simplified to the target of the edges only,
since swaping sources is redundant.

The number of iterations can now be explicitly modified, so it is not
necessary to call the function more than once, and it is emphasized in
the documentation that only after sufficiently many iterations can the
graph be guaranteed to be fully mixed.

This fixes a bug where filtered vertices would be incorrectly marked, if
the largest component index happend to be zero.

This fixes a leftover bug from the removal of the 'core' submodule.

Added more DOI links to references, and other cosmetic changes.

This allows for sampling of random subgraph isomorphisms.